When we think of plastic pollution, we often picture bottles and bags floating in the ocean. But not all plastic is immediately visible. In the Port of Rotterdam, tiny industrial pellets — known as nurdles — are leaking into the environment, causing a form of pollution that’s hard to trace but highly persistent.
by Sifra Hordijk
As part of the LDE Sustainability Honours Programme, students Laurence Krakow, Sarayesha Fazila, Elvire Meijer, Emma Solé de la Fuente and Thijmen Ploos van Amstel took on a sustainability challenge set by the Port of Rotterdam Authority: to help identify the sources of this pellet pollution.
By combining environmental data, stakeholder input and spatial analysis, they developed an interactive map to identify possible sources of leakage. We spoke with Laurence, Sarayesha and Elvire about what they discovered and what they learned from tackling a complex sustainability challenge.
The Sustainability Challenge
“Before this project, I’d never even heard of nurdles,” said Laurence, who studies Applied Earth Sciences at TU Delft. “In the Port of Rotterdam, these pellets are found everywhere, spilled during production, loading or transport, and gradually leaking into the surrounding waters.”
“The Clean Sweep Taskforce, a collaboration between companies, the Port of Rotterdam Authority, and government bodies, has already taken steps to address the issue. However, despite ongoing clean-up efforts, the nurdles continue to reappear. To better understand the problem, the taskforce invited a group of students to investigate. ‘They asked us to pinpoint potential sources of this plastic pollution,’ explained Sarayesha, a student of International Economics and Business Economics at Erasmus University.”
Tracing the source
The student team began their research by reviewing literature and speaking with experts from the Port of Rotterdam and local environmental authorities. One of the most valuable tools they received was a hotspot map.
“We started by looking at a hotspot map created by the taskforce, showing where nurdles had been found,” said Elvire, a biology student at Leiden University. “Then we checked which companies were nearby and what kind of companies they were. We divided them into four categories: production, transportation, recycling, and sales.”
To deepen their analysis, the team consulted environmental permits from the DCMR database. “We used the data to find out what these different companies produce and in what quantities,” explained Laurence. “Then we compared that to estimates of how much plastic is typically spilled during production, to get a rough idea of how much might be leaking within the port and how much could be coming from outside.”
Another important part of the project was a meeting with Lennart Keyzer, an expert from the port, who explained how water currents and wind might carry the pellets. This helped the students explore whether the nurdles could be entering the port from elsewhere, for instance, via the North Sea or the Rhine.
Main findings and next steps
Although the team didn’t identify a single source of the pollution, their research led to several practical recommendations for the Port of Rotterdam. One key suggestion was to invest in better modelling tools to track the movement of plastic pellets through the port area. “Oil spills can be modelled quite accurately because there’s a lot of research,” noted Laurence. “But with plastic pellets, we’re just not there yet.”
The students advised the Port to combine wind and flow data to better understand how nurdles spread after a spill. However, they also pointed out a technical limitation: “The Port only has wind models at a resolution of around 100 metres,” Laurence explained. “That’s not precise enough, especially because near the surface, buildings and other obstacles really affect the wind.”
Insights from their meeting with expert Lennart Keyzer supported this analysis. “The port is an estuary, and salt and fresh water don’t really mix,” Sarayesha explained. “So, it is highly likely that pellets enter the port from outside. However, they probably arrive in greater numbers from upstream than from the open sea.”
To support future action, the team developed an interactive digital map that brings together all relevant data including hotspots, nearby companies and the types of activities taking place. “It’s a tool the Port can update over time as new information becomes available,” Elvire explained.
Why the LDE Sustainability Honours Programme?
One of the unique features of the LDE Honours Programme is its interdisciplinary approach, which brings together students from different universities, academic backgrounds and cultures. For all three students, the programme was an opportunity to step outside the boundaries of their regular studies and work on a concrete sustainability issue.
“In my biology programme, we focus mainly on the scientific side. I wanted to better understand the social and economic factors that also play a role. Since my studies are in Dutch, I don’t often work with international students. This programme gave me the chance to work in a much more diverse environment,” said Elvire. Laurence agreed: “I wanted to do something a bit different, something that involved more creative thinking and solution design.”
Beyond the academic challenge, the students appreciated the level of engagement from the Port of Rotterdam. “Our collaboration with them was very positive,” said Sarayesha. “They were really open and happy to have a group of students to try and help out, even for a short period of time. They gave us a tour, received us for meetings, and even trusted us to present our findings in front of the whole taskforce.”
Reaction Imke Deibel (Advisor Environmental Management, Port of Rotterdam):
We asked the LDE Sustainability Honours Programme to take on this challenge, because the issue with plastic nurdles lacks a straightforward solution. We were pleased to have a multidisciplinary team to explore fresh perspectives, without steering them in a specific direction. While extensive chemical analyses might seem like the obvious route, they are costly and potentially ineffective.
Instead, the students creatively combined company data with flow model recommendations—an approach we’re keen to develop further. The collaboration was excellent, with diverse expertise coming together seamlessly. The students worked independently, remained engaged, and regularly shared updates. I was genuinely proud to see them present their findings to the entire taskforce with such confidence and professionalism.