Vonberg D.,Julich Research Center |
Vanderborght J.,Julich Research Center |
Cremer N.,Erftverband |
Putz T.,Julich Research Center |
And 2 more authors.
Water Research | Year: 2014
Atrazine was banned in Germany in 1991 due to findings of atrazine concentrations in ground- and drinking waters exceeding threshold values. Monitoring of atrazine concentrations in the groundwater since then provides information about the resilience of the groundwater quality to changing agricultural practices. In this study, we present results of a monitoring campaign of atrazine concentrations in the Zwischenscholle aquifer. This phreatic aquifer is exposed to intensive agricultural land use and susceptible to contaminants due to a shallow water table. In total 60 observation wells (OWs) have been monitored since 1991, of which 15 are sampled monthly today. Descriptive statistics of monitoring data were derived using the "regression on order statistics" (ROS) data censoring approach, estimating values for nondetects. The monitoring data shows that even 20 years after the ban of atrazine, the groundwater concentrations of sampled OWs remain on a level close to the threshold value of 0.1μgl-1 without any considerable decrease. The spatial distribution of atrazine concentrations is highly heterogeneous with OWs exhibiting permanently concentrations above the regulatory threshold on the one hand and OWs were concentrations are mostly below the limit of quantification (LOQ) on the other hand. A deethylatrazine-to-atrazine ratio (DAR) was used to distinguish between diffuse - and point-source contamination, with a global mean value of 0.84 indicating mainly diffuse contamination. Principle Component Analysis (PCA) of the monitoring dataset demonstrated relationships between the metabolite desisopropylatrazine, which was found to be exclusively associated with the parent compound simazine but not with atrazine, and between deethylatrazine, atrazine, nitrate, and the specific electrical conductivity. These parameters indicate agricultural impacts on groundwater quality.The findings presented in this study point at the difficulty to estimate mean concentrations of contamination for entire aquifers and to evaluate groundwater quality based on average parameters. However, analytical data of monthly sampled single observation wells provide adequate information to characterize local contamination and evolutionary trends of pollutant concentration. © 2013 Elsevier Ltd.
Verrecht B.,Cranfield University |
Maere T.,Ghent University |
Nopens I.,Ghent University |
Brepols C.,Erftverband |
Judd S.,Cranfield University
Water Research | Year: 2010
A cost sensitivity analysis was carried out for a full-scale hollow fibre membrane bioreactor to quantify the effect of design choices and operational parameters on cost. Different options were subjected to a long term dynamic influent profile and evaluated using ASM1 for effluent quality, aeration requirements and sludge production. The results were used to calculate a net present value (NPV), incorporating both capital expenditure (capex), based on costs obtained from equipment manufacturers and full-scale plants, and operating expenditure (opex), accounting for energy demand, sludge production and chemical cleaning costs.Results show that the amount of contingency built in to cope with changes in feedwater flow has a large impact on NPV. Deviation from a constant daily flow increases NPV as mean plant utilisation decreases. Conversely, adding a buffer tank reduces NPV, since less membrane surface is required when average plant utilisation increases. Membrane cost and lifetime is decisive in determining NPV: an increased membrane replacement interval from 5 to 10 years reduces NPV by 19%. Operation at higher SRT increases the NPV, since the reduced costs for sludge treatment are offset by correspondingly higher aeration costs at higher MLSS levels, though the analysis is very sensitive to sludge treatment costs. A higher sustainable flux demands greater membrane aeration, but the subsequent opex increase is offset by the reduced membrane area and the corresponding lower capex. © 2010 Elsevier Ltd.
WIT Transactions on Ecology and the Environment | Year: 2014
Monitoring activities for detecting micropollutant concentration ranges have been developed for the Swist river in the German state of North Rhine- Westphalia. The monitoring program covers various point and non-point emission input sources as well as immissions in the watercourse and takes regional factors such as climate, land use and population density into consideration. Data for a relatively large number (up to 160) and broad range of anthropogenic micropollutants (e.g. pharmaceuticals, pesticides and industrial chemicals) has been gathered and analysed. Substance loads at wastewater treatment plant outlets as well as within the river are calculated from flow data and substance concentrations. Sampling times are defined according to season and weather conditions. Knowledge has been gained regarding temporal and spatial variation in the appearance of micropollutants and the requirements for a monitoring program to cover these fluctuations. Moreover, experience has been gained in mass flow analysis and emission balancing. © 2014 WIT Press.
WIT Transactions on Ecology and the Environment | Year: 2013
A clear picture of the dynamic processes of river water quality, in particular for a river such as the Erft with low mean water flow combined with intensive water use, cannot be obtained through simple spot checks. For this reason, twenty-three years ago the Erftverband, a water management association in North Rhine-Westphalia (Germany), initiated an online monitoring network consisting of six water quality monitoring stations for continuous recording of contents of surface water in the Erft catchment. Measurement data combined with physicochemical and biological data from routine spot checks is processed at a central facility to yield information needed to assess and if necessary to improve water quality. Examples of such information are presented. The considerable advantages for river basin management planning are disclosed. © 2013 WIT Press.
WIT Transactions on Ecology and the Environment | Year: 2012
The DWA water quality model can be used for a wide range of water management planning activities. Fields of application extend from data and system analysis, to the analysis of alternatives in water pollution control planning, to the implementation of alarm plans. The example of the Erft river is used to present the results of water quality simulations with a view to assessing current conditions and forecasting the future development of water quality. © 201 WIT Press.