The European dredging industry produces an estimated 200,000,000 m3 of sediment per year. The vast majority of this material is a mixture of very fine sediment and water. In order to create soil from this watery sludge, dredging companies typically have to wait for long periods of time as the water drains or evaporates away naturally. This is called dewatering.
Medeina – one of PortXL’s cohort of 2023 start-ups – discovered a way to significantly speed up the dewatering process. The method is based on a rather special combination of biology and physics; the star of the show is actually……a worm. The 2-5 cm in length, 0.2-0.3 mm in cross section Tubifex tubifex, to be precise. Below, Medeina co-founder and CEO Miguel de Lucas discusses how this humble little worm could be a potential game-changer for the dredging (and civil engineering) industries.
PortXL: How did you come across the idea of combining physics and biology to dewater dredged sediments?
MdL: I was studying sediment dynamics, looking at how particles of soil settle in a water column, how this forms an aggregate, ultimately becoming a bed, which loses water to become soil. This is usually described from a physics perspective using complex equations and coefficients, but I noticed that if there is something alive in the sediment, this changed the results by as much as 200 percent in either direction. I thought to myself: ‘why am I studying the physics if everything is dominated by the biological side of it?’
How did you take this observation further?
I started working with worms for the first time during my PhD, starting with 100ml of sediment, then 500ml, increasing over the years until 36 cubic metres. I have only collected positive results from these experiments: sediments with worms get rid of water faster.
You are working with a worm called Tubifex tubifex. Why is this particular worm so special?
I have tested six different types of worm – marine, aquatic and terrestrial – and I have found that Tubifex tubifex is the best for dewatering because it tolerates more anoxia and higher levels of environmental contamination than any other worm that we know of. What’s more, they like to deposit their faeces on the water/mud interface. In doing this, Tubifex creates a lot of vertical tunnels and this is great for dewatering.
So, is this more physics than biology?
It’s mainly because of the physics. When you put these worms in a watered sediment, they will make a network of tunnels throughout the entire volume of sediment. Water will drain from this tunnelled sediment far quicker than from non-tunnelled sediment.
Medeina’s website shows that you work with plants and algae too. Which is the best for dewatering?
If I had to rank the different methods, then I would say that worms start off at number one. The combination of worms and plants are number two. Plants on their own are number three – although after a few months they actually become the best dewatering agent. The use of algae, on the other hand, is envisioned to assist in flocculation, but not in dewatering.
You have proved the science behind Tubifex and dewatering. At what stage is Medeina now?
Since founding Medeina in June 2022, we have been busy lining up stakeholders that want to work with us. Everybody is excited about the research results that we have collected, so now we are ready to carry out a pilot project. The focus of Medeina is in solving the practical issues related to large scale application, like for example the supply of worms at a competitive price.
How big will the pilot project be? How much sediment?
This will be 1,000 cubic metres, which is a 100 by 10 area that is one metre deep. One metre deep is the preferred depth of sediment from the dredging industry’s point of view.
Now that you are part of the PortXL acceleration programme, what do you want to achieve in the year ahead?
Thanks to PortXL, we hope to make a fast and efficient transition into the pilot project phase. I hope that next year, Medeina’s work will have been successfully demonstrated at scale to be both economically and technically efficient.
Want to know more? Check Medeina’s website or contact PortXL for info on (public) events where you can meet their Team.