If we are to be able to properly respond to the latest developments – think drought or newly discovered pollutants – research into the theme of Purification remains crucial. In addition to current research projects, new ones are therefore continually being scheduled. Theme ambassador Abel Heinsbroek explains some of them.
“To date, we at Vitens have applied almost exclusively groundwater extraction and bank filtration for the production of drinking water. We have extraction permits that specify the volume of groundwater we may extract per month and per year. In recent hot and dry summers, however, we already witnessed that our customers’ demand for water in some areas exceeded these levels. One of the methods we apply in our endeavour to tackle this problem is to encourage our customers to use water both sparingly and consciously. Despite this policy, we expect to reach the limits of our extraction permits more often in the coming years. Given that the development of new groundwater extraction sites can easily take a decade or longer, we are to launch two projects that investigate the possibilities of using surface water as a raw material.”
“The first of the projects is to examine whether we might produce ultrapure water by applying reverse osmosis membranes to remove all unwanted substances from surface water. We subsequently intend to blend this ultrapure water with purified groundwater. Should this prove feasible, we will proceed to construct a membrane system that is both modular and can be conveniently assembled and disassembled. This would enable us to swiftly deploy the system in areas where we cannot – temporarily or otherwise – extract sufficient groundwater and where we have insufficient control of the quality of the surface water used.”
“If one could succeed in removing only the problematic substances, it would yield a far more efficient solution.”
Abel continues: “One of the disadvantages of reverse osmosis is that it involves high energy consumption. Moreover, the water produced is not immediately suitable for human consumption, as all the minerals have been removed. We are therefore keen to investigate whether membrane filtration might prove suitable for the direct production of reliable drinking water. After all, the ability to remove solely problematic substances would yield a far more efficient solution. To carry out trials with this purification technique, we intend to construct a pilot plant alongside the River IJssel, which will have to run for at least a year. This should enable us to establish whether membranes serve as a sufficiently effective barrier, how quickly they become clogged and how they behave in the long term. It is also an opportunity for Vitens to simultaneously acquire vital experience in the purification of new sources and all that this might entail.”
Abel goes on to explain that another research project involves the construction of a test bed in Friesland. “Our ultimate aim is to develop a completely new purification system there, which applies all the innovative techniques we have researched at other production sites in recent years. We trust that this will enable us to design the most sustainable, innovative and energy-efficient purification system. Trials are scheduled to commence next year. We intend to build three parallel purification lines – one that applies conventional techniques, while the other two feature a combination of innovative technologies – to establish which operates most favourably over the course of the year. We will then equip the new treatment plant with them.
“Another project again involves research into the removal of PFAS. These toxic substances deteriorate very gradually, if at all, and are becoming highly abundant in the environment. This implies that water companies such as ourselves need to devote increasing attention to these harmful substances. Our existing treatment plants have so far succeeded in removing PFAS by means of activated carbon and membrane filtration. In anticipation of the fact that surface water will increasingly serve as the basis for our drinking water production, we intend to carry out model-based research into the removal of PFAS by means of carbon filtration.”
“We are keen to avoid releasing a potent greenhouse gas like methane into the air, and are therefore looking for useful applications that reduce the environmental impact.”
Vitens increasingly extracts dissolved methane from the groundwater at its various production sites. Abel: “Methane is a potent greenhouse gas. We are keen to avoid simply releasing extracted methane into the air, and are therefore looking for useful applications that reduce the environmental impact. We are collaborating closely with the team from the Circular Economy and Society theme in this regard. Given that the amount of gas extracted differs per site, as do possible applications in the immediate vicinity – e.g., using the methane to heat properties or mixing it with the biogas produced by a manure digester – we need to map the most favourable applications at each particular site. Should the search fail to yield a feasible application, however, we could simply opt to flare the gas, as the environmental impact of the resulting CO₂ emission is significantly lower than that of methane itself.
The final innovation project Abel mentions is aimed at the development of a pellet reactor for the deferrisation of groundwater: “In collaboration with Delft University of Technology, we are to examine the possibilities of developing a continuous process for the removal of iron, thus avoiding the need to backwash sand filters in future. We are currently considering the use of a compact pellet reactor, which promotes the adsorption of a layer of iron to the granular filter material, which then need only be replenished now and then. We are due to launch a small scale pilot programme at our production company in Wierden in the spring of 2022.”
Would you like to contribute to the efforts Vitens’ innovation programme is making within this theme? In that case, please contact us through: firstname.lastname@example.org
*This is an article from the magazine Vitens Innovates – Purification theme.
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