In several Vitens’ wellfields, water quality varies greatly from well to well. This has adverse consequences for the treatment of the abstracted water. Over the past few years, the water company has developed various concepts aimed at improving and stabilising the quality of the raw water, such as the real-time on/off switching of wells, and the optimisation of switching systems (SLIMM and SLIMM2). Apart from smarter management, Vitens also has experience with the separate abstraction from wells of different water qualities. In addition, a test is being conducted with the Freshmaker, which involves capturing brackish water below a recovery well.
This project focuses on two Vitens’ production locations: Ellecom and Sint Jansklooster, which, due to their subsurface spatial heterogeneity, experience fluctuations in the quality of the raw water collected, and a corresponding drop in treatment performance. The objective is to formulate and evaluate possible solution tracks, with the aim of improving the quality of the raw water over the long term through (1) smart management with soft sensors, and (2) implementation of other operational measures, such as the separate abstraction of different groundwater types by redesigning the wellfields.
Smart management and additional measures
We conduct a geohydrological system analysis to have a good (conceptual) model of the subsurface and the wellfield. We then conduct a sensitivity analysis to determine whether any supplementary field measurements are required for the solutions’ calculation, and, if so, which.
With regard to the supplementary measurements, there are a number of options:
- High-frequency measurements of well heads and well switching (Ellecom).
- Depth profile of water quality (Ellecom).
- High-frequency measurements of raw water quality by well (Sint Jansklooster).
- Validation of soft sensors (Sint Jansklooster).
Depending on the results, we carry out an update of the system analysis. We then formulate a combined solution tracks per abstraction site. We elaborate these solution tracks and evaluate them. For Sint Jansklooster, where Vitens will be developing a soft sensor, we draw up supplementary operational rules for the further optimisation of the wellfield. Coordination during the project is good, thanks to interim consultations and because our staff is regularly working onsite at Vitens.
Cost savings and more effective treatment process
A smart organisation and optimisation of production at the Ellecom and Sint Jansklooster sites result in big cost savings. In addition, a more even load leads to a more effective operation of the treatment process. Additional benefits include a decrease in the environmental impact (sustainability, reduced CO2 footprint), and fewer operational disruptions (supply security).
The findings of the research are widely applicable. For example, the research aims to provide insight into techniques to optimise management of wellfields in an integrated manner. This involves taking into account not only momentary parameters, such as fluctuations in raw water quality and energy consumption due to the suppression of wells, but also the long-term effects on water quality and well clogging. The latter receives a lot of attention within Vitens, but is not yet explicitly incorporated in SLIMM2.