What is your job as a policy advisor for circular economy?
“Sustainable Innovation (Duurzaam Vernieuwen)” is a change programme at our water authority Vallei en Veluwe for the energy transition, circular economy and CO² reduction.
It is my goal to implement and develop a route to achieve our long-term goals for 2030 and 2050. It is our goal to be energy neutral in 2025 and climate positive and completely circular by 2050. We have already become energy neutral at our biogas plants, by applying sludge digesters. And we have also built solar farms next to some of our wastewater treatment plants. At this moment, we are designing our WWTP in Terwolde– which will be our second Nereda plant – to be as circular as possible. This includes using the 10R-ladder for design, our material choices, reusing some of the existing asset and including Verdygo.
What is your background?
I studied laboratory techniques and then went to work at DHV as a water research engineer. I was working in the laboratory and carrying out pilot work, startup of treatment plants and full commissioning. Later I joined water authority Vallei and Veluwe. After being employed there for a few years I saw opportunities to do more within circular economy and sustainable wastewater treatment. Since these topics really excited me, I decided to take an associate degree in environmental studies at VHL in Leeuwarden. The studies were focused on solving environmental problems and addressing sustainability through alternative technologies and policies. It taught me everything about how we affect the water as humans on a broad scale, and it really inspired me to make changes around me.
How can WWTP become more sustainable?
There are several ways for WWTPs to become more sustainable, both in the short-term and long-term. In the short-term, WWTPs can be optimised in several ways and slightly redesigned, which can reduce the energy costs. Most of our existing plants were designed and built in the 1960’s and 70’s. We could replace (inefficient) surface aeration with bubble-aeration to save up to 25% of electric energy. Moreover, back then, heat coming from the CHP’s was only used for heating
the digesters and the buildings on site. At times, heat was released with coolers into the air. We now regard heat as thermal energy and try to find consumers for it.
Furthermore, resource recovery, such as bioplastics and phosphorous for instance, has huge potential. Making the transfer from chemical to biological P-removal also has a huge impact on the environment, like in our Nereda plants in Epe and Terwolde. As for in the long-term, doing more local wastewater treatment, for instance within one suburb or street, would also make the treatment process more sustainable. This would help reduce the energy use for transport of the wastewater and keep the treated water within areas that are now influenced by draught. In addition, water factories, like the one we are piloting and designing in Wilp, are also what I see as the future of sustainable wastewater treatment. In Wilp, we will be using a new purification concept called “the Waterfactory” to make clean water to prevent drought in the area and raw materials will be extracted from the wastewater.
What can you do to decrease the environmental impact of a new wastewater treatment plant?
If you want to improve the environmental impact of a new wastewater treatment plant, you should already look at what you can do in the design phase and what sort of materials you use. A wooden bridge will maybe only last 20 years, but it will take up CO² whereas steel will last forever but has a huge CO²-footprint. So, it is not always about the lifetime of the used material
but more about which material has the least impact on the environment during its life cycle. Reuse and repair are also extremely important parts. Machines must be built to last longer, and tools and equipment should always be repaired as a first option, instead of throwing them away.
It seems logical, but we are currently living in a linear economy, where use and throw away has become the normal way.
It’s important to think about the surrounding areas of the wastewater treatment plant. We used to put grass everywhere because it’s easy to maintain, but it is actually better to plant flowers and trees to strengthen the biodiversity in the area. It looks a bit messier to people that are used to see cleanly mowed lawns, but we have to change our mindset and get used to that look. At our Nereda plant in Terwolde, we also constructed the operations building with a green roof and walls.
What have you done at water authority Vallei and Veluwe to improve sustainability?
We are currently working on the implementation of DOW (Duurzaam opdrachtgeverschap
Waterschappen – sustainable commissioning). This means that for every service purchased or job that you do, you must follow the most sustainable route and use tools like the ambition web and CO²ladder, and use Dubocalc to calculate the environmental costs. At the beginning of a new project, the questions that you always need to ask yourself are:
Do I need to do this and if so, how can I do it with the lowest impact?
By thinking about everything from social economy to CO² footprint every time you do a task, you will eventually become more sustainable. It’s a learning process.
In this calculation, sustainability versus costs is naturally always an important consideration. You may save some costs now by choosing a lower cost option in euros today, but instead leave
behind a huge cost burden for the next generation by postponing choosing a sustainable solution.
As a water authority, we are funded through taxes and naturally do not have unlimited money
to invest. So, we have to find ways to not make the sustainable investments more costly, but instead more effective and try to find clever ways to reuse and optimise.
How do you see the future in wastewater treatment?
As I mentioned earlier, I really see the future of sustainable wastewater treatment in steps of short-term, middle-term, and long-term. Important themes in the near future will be nutrient recovery and using wastewater treatment as an energy source from which you can retrieve heat. What will be most important to achieve our goals in the future is cooperation. As a water
authority, we need to work on this closely together with researchers, universities, engineering companies and suppliers. We need to cooperate with companies and suppliers to develop new technologies and solutions. Take sludge dewatering for instance. We use a lot of energy and chemicals in this process. Here we need to find a bio-based solution together with the suppliers in the short term, develop other dewatering techniques in the middle-term and not produce sludge in the long-term. You cannot achieve a Circular economy by yourself, you need every partner in the chain. In the end, the whole picture comes together in the operation.