inproceedings by Geert Dirckx
9th IWA Symposium on Systems Analysis and Integrated Assessment, 2015
In order to comply with the effluent norms, wastewater operators need to avoid hydraulic overload... more In order to comply with the effluent norms, wastewater operators need to avoid hydraulic overload of their wastewater treatment plants (WWTP), as this can entail the wash out of activated sludge from the secondary settling tanks. This can become a problem when extending existing transport infrastructure.
articles by Geert Dirckx
Skip to Next Section The paradigm shift in recent years towards sustainable and coherent water re... more Skip to Next Section The paradigm shift in recent years towards sustainable and coherent water resources management on a river basin scale has changed the subject of investigations to a multi-scale problem representing a great challenge for all actors participating in the management process. In this regard, planning engineers often face an inherent conflict to provide reliable decision support for complex questions with a minimum of effort. This trend inevitably increases the risk to base decisions upon uncertain and unverified conclusions. This paper proposes an adaptive framework for integral planning that combines several concepts (flow balancing, water quality monitoring, process modelling, multi-objective assessment) to systematically evaluate management strategies for water quality improvement. As key element, an S/P matrix is introduced to structure the differentiation of relevant `pressures' in affected regions, i.e. `spatial units', which helps in handling complexity. The framework is applied to a small, but typical, catchment in Flanders, Belgium. The application to the real-life case shows: (1) the proposed approach is adaptive, covers problems of different spatial and temporal scale, efficiently reduces complexity and finally leads to a transparent solution; and (2) water quality and emission-based performance evaluation must be done jointly as an emission-based performance improvement does not necessarily lead to an improved water quality status, and an assessment solely focusing on water quality criteria may mask non-compliance with emission-based standards. Recommendations derived from the theoretical analysis have been put into practice.
In spite of considerable uncertainty reported on the impact of Combined Sewer Overflows (CSO), it... more In spite of considerable uncertainty reported on the impact of Combined Sewer Overflows (CSO), it is generally acknowledged to not be negligible. Not surprisingly CSO impact is considered \textendash{} although indirectly \textendash{} in driving European legislations regarding the wastewater pollution and treatment. Still, when looking at impact reduction, policy makers tend to resort rather to static solutions such as disconnection or the building of storage tanks. On the other hand they often seem to be put off by dynamic measures such as Real Time Control (RTC) of sewage systems because of its perceived complexity. This paper describes a cost-benefit analysis of several static and dynamic solutions to mitigate CSO impact, based on the case-study of the Kessel-Lo catchment in Flanders/Belgium. RTC turned out to be not only the most cost efficient measure for CSO impact mitigation but also the solution offering the most flexibility for further system upgrade.
Water Science and Technology, 2016
In order to comply with effluent standards, wastewater operators need to avoid hydraulic overload... more In order to comply with effluent standards, wastewater operators need to avoid hydraulic overloading of the wastewater treatment plant (WWTP), as this can result in the washout of activated sludge from secondary settling tanks. Hydraulic overloading can occur in a systematic way, for instance when sewer network connections are extended without increasing the WWTP's capacity accordingly. This study demonstrates the use of rule-based real-time control (RTC) to reduce the load to the WWTP while restricting the overall overflow volume of the sewer system to a minimum. Further, it shows the added value of RTC despite the limited availability of monitoring data and information on the catchment through a parsimonious simulation approach, using relocation of spatial system boundaries and creating required input data through reverse modelling. Focus was hereby on the accurate modelling of pump hydraulics and control. Finally, two different methods of global sensitivity analysis were employed to verify the influence of parameters of both the model and the implemented control algorithm. Both methods show the importance of good knowledge of the system properties, but that monitoring errors play a minor role.
Papers by Geert Dirckx
Water Practice & Technology, 2013
This study presents the development of an Early Warning System (EWS) called EPIGONE focusing on t... more This study presents the development of an Early Warning System (EWS) called EPIGONE focusing on the detection of dry weather overflows in the vicinity of throttle structures in sewer systems. Throttle structures are considered as vital parts of a sewer system as they are control sections limiting flow rates to a designed operational value. Because these structures are by definition prone to potential clogging or blockages, a close follow-up of the daily operation by an EWS facilitates increased vigilance or even alarm. Primary goal of EPIGONE is to alert operators and thus allow fast intervention in case of suspected failures of these structures within a settled timeframe. EPIGONE combines overflow water level measurements with rainfall radar information to determine Combined Sewer Overflow (CSO) activity during dry weather as this dual condition will indicate malfunctioning. This combination of measurements was found to be the most cost effective set-up to deploy on a large scale. ...
Water science and technology : a journal of the International Association on Water Pollution Research, 2005
This work was aimed at performing an analysis of the integrated urban wastewater system (catchmen... more This work was aimed at performing an analysis of the integrated urban wastewater system (catchment area, sewer, WWTP, receiving water). It focused on analysing the substance fluxes going through the system to identify critical pathways of pollution, as well as assessing the effectiveness of energy consumption and operational/capital costs. Two different approaches were adopted in the study to analyse urban wastewater systems of diverse characteristics. In the first approach a wide ranged analysis of a system at river basin scale is applied. The Nete river basin in Belgium, a tributary of the Schelde, was analysed through the 29 sewer catchments constituting the basin. In the second approach a more detailed methodology was developed to separately analyse two urban wastewater systems situated within the Ruhr basin (Germany) on a river stretch scale. The paper mainly focuses on the description of the method applied. Only the most important results are presented. The main outcomes of th...
Driven by (receiving) water quality based legislation, in particular the Water Framework Directiv... more Driven by (receiving) water quality based legislation, in particular the Water Framework Directive, European waste water utilities face the challenge to contribute (though indirectly) to the Good Ecological Status of the water courses that are influenced by their infrastructure. Historic data sets of registered pollutants discharged by CSO"s have proven the relevance of CSO spills regarding pollution impact. From a wastewater operator prospective this makes the reduction of CSO impact one of the key measures towards a compliance with the current legislation. This paper describes a cost-benefit analysis of several static (disconnection, storage tanks and adjustment of throttle pipes) and dynamic solutions (RTC) to mitigate CSO impact, based on the case-study of the Kessel-Lo catchment in Flanders/Belgium. Emphasis was on exploring the potential of implementing Real Time Control (RTC) of sewage systems. RTC turned out to be the most cost efficient measure for CSO impact reduction.
Water Science & Technology, 2012
The paradigm shift in recent years towards sustainable and coherent water resources management on... more The paradigm shift in recent years towards sustainable and coherent water resources management on a river basin scale has changed the subject of investigations to a multi-scale problem representing a great challenge for all actors participating in the management process. In this regard, planning engineers often face an inherent conflict to provide reliable decision support for complex questions with a minimum of effort. This trend inevitably increases the risk to base decisions upon uncertain and unverified conclusions. This paper proposes an adaptive framework for integral planning that combines several concepts (flow balancing, water quality monitoring, process modelling, multi-objective assessment) to systematically evaluate management strategies for water quality improvement. As key element, an S/P matrix is introduced to structure the differentiation of relevant ‘pressures’ in affected regions, i.e. ‘spatial units’, which helps in handling complexity. The framework is applied t...
Water Science & Technology, 2011
Combined sewer overflows (CSO) are the ''ugly ducklings'' of urban wastewater infrastructure, rat... more Combined sewer overflows (CSO) are the ''ugly ducklings'' of urban wastewater infrastructure, rather unknown, rarely loved. Contrary to wastewater treatment plants (WWTP) where, commonly, process parameters are carefully registered, still relatively little is known about the spill behaviour of CSOs. In spite of the considerable bandwidth of pollution magnitude reported in literature, it can be generally accepted that CSO impact certainly is not negligible. As the sole wastewater utility in Flanders (6,100,000 inhabitants), Aquafin operates, next to 230 WWTP's and almost 1,000 pumping stations, some 3,100 CSOs. In search for an optimum CSO management strategy, Aquafin prospected several modelling and monitoring possibilities. As a result, a CSO action plan could be drawn up tailored to the estimated relevance of the CSO under consideration. In a further step a cost-benefit analysis of several static and dynamic remediation measures was undertaken. Real Time Control (RTC) strategies turned out to be the most cost efficient solution for CSO impact mitigation.
Urban Water Journal, 2009
Dilution of wastewater in sewerage networks is a major concern for wastewater operators. To tackl... more Dilution of wastewater in sewerage networks is a major concern for wastewater operators. To tackle this problem on a regional scale, the Flemish wastewater operator Aquafin developed software enabling the prioritisation of intervention, highlighting the so-called dilution wet spots in the region in a transparent and straightforward way. Quantitative assessment reveals that in 108 of the 194 investigated catchments more than 50% of the dry weather flow is due to dilution. In the search for a hands-on, accurate method that could reveal the major inputs of infiltration and inflow within a sewer system, a promising tracing method based on isotopes was tested on two different case studies. To verify the application potential of such a method on a regional scale (Flanders), the isotope contents of drinking water and groundwater were compared for 65 catchments, with contrasting results.
Urban Water Journal, 2008
ABSTRACT Transport behaviour of a particle under certain flow conditions is mainly defined by its... more ABSTRACT Transport behaviour of a particle under certain flow conditions is mainly defined by its geometric and physical properties. Besides, the pollution potential of sewer sediments depends strongly on size and origin. This paper presents an approach for keeping track of freely defined particle classes. A total load transport model was modified to facilitate fraction wise transport and distinguish between sedimentation and erosion as two different processes. Compared to approaches using only one characteristic diameter modelled transport rates are in the same order of magnitude but with additional information of size distribution and origin. A virtual case study shows the general applicability. Main constraint is the increase of model parameters and data needs.
Urban Water Journal, 2006
The holistic approach to water resources management introduced by the EU Water Framework Directiv... more The holistic approach to water resources management introduced by the EU Water Framework Directive (WFD) implies the adoption of methodologies that are suitable to reveal the major pressures and impacts on the receiving waters at river basin level in an effective and efficient way. This study investigated the general adequacy of substance flow analysis (SFA) for the analysis of urban wastewater systems (urban catchment, sewer, WWTP, receiving water). The paper provides a description of the approach and a useful demonstration of the method through the illustration of a case study. The study considered the fluxes of six substances going to, through and from the wastewater management system. The results suggest that the proposed methodology can be used for the identification of stressors on the receiving water bodies and highlights that the scale dependency of results in such studies is of primary importance.
Urban Water Journal, 2011
In spite of considerable uncertainty reported on the impact of Combined Sewer Overflows (CSO), it... more In spite of considerable uncertainty reported on the impact of Combined Sewer Overflows (CSO), it is generally acknowledged to not be negligible. Not surprisingly CSO impact is considered – although indirectly – in driving European legislations regarding the wastewater pollution and treatment. Still, when looking at impact reduction, policy makers tend to resort rather to static solutions such as disconnection or the building of storage tanks. On the other hand they often seem to be put off by dynamic measures such as Real Time Control (RTC) of sewage systems because of its perceived complexity. This paper describes a cost-benefit analysis of several static and dynamic solutions to mitigate CSO impact, based on the case-study of the Kessel-Lo catchment in Flanders/Belgium. RTC turned out to be not only the most cost efficient measure for CSO impact mitigation but also the solution offering the most flexibility for further system upgrade.
Journal of Environmental Management, 2008
In order to comply with the Water Framework Directive's requirement to reveal the major pressures... more In order to comply with the Water Framework Directive's requirement to reveal the major pressures and impacts on the receiving water at river basin level, the merits of a methodology that combines substance flow analysis and mass balances were evaluated with the aid of a case study. The river basin analysis consisted of the analysis of all individual municipal sewer catchments constituting the basin on a yearly time scale, and included the description of the main sewers and waste water treatment plants and their performance in environmental and economical terms. A wide set of indicators was evaluated. Uncertainties and information gaps arising from the study are described. The choice of the geographic scale seems a key factor in the evaluation. The case study indicates that such an evaluation is of great value for decision-makers in the perspective of the Water Framework Directive implementation, to highlight situations of weak or strong performance and to pinpoint information gaps requiring further research in order to take more informed decisions, to identify the main pressures on the environment and to plan more cost-effective measures.
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inproceedings by Geert Dirckx
articles by Geert Dirckx
Papers by Geert Dirckx