Behind the PhD degree: Olga Sójka

Technology is a direct tool to tackle some of our world’s problems, according to PhD candidate Olga Sójka. And wouldn’t it be nice if everyone had it nice – is her philosophy. So, she dedicated a part of her life to finding these solutions. Having finished her research on preventing bacterial growth in essential drinking water distribution systems, she is proud that she could make a difference and is still happy to do more.

The people behind the science, and the science behind the people

A productive way to make a change

With empathy as a core talent, Olga has always felt a need to make a difference for others. It was her drive to do a degree in Environmental Protection Engineering, covering a wide range of topics from water through soil to solid waste management. But it’s water that spoke to her most. ” The versatility of water technologies struck me, and I found that the Water Technology master at Wetsus was the perfect match,” the young researcher decided.

“It was a great experience, my first working in the international environment. Here in the Netherlands, you are much more focused on innovation as opposed to conservative practicality in Poland. At the Water Technology master, we had a chance to visit multiple facilities, which showed us that innovative technologies can provide solutions beyond wastewater treatment. We learnt that wastewater is not waste, but a source of valuable resources. At Wetsus, they see this and they focus on providing tools to make a change.”

After her graduation, she has worked as a water technologist first. But it wasn’t for her. Olga: “While working in the industry, I struggled with the profit-driven approach, which often rushed the delivery of solutions without a proper investigation. I was missing the depth which made me think of returning to research. ” Back to Wetsus, it was.

Nanogel coatings

The persistent researcher eventually found herself in the Biofilms theme. Her goal: to translate the biomedical experience in preventing biofilms to developing bacteria-repelling layers applicable in drinking water distribution systems. These coatings are now used in medical implants, for instance.

“Hydrogels are soft swelling materials that hold water. In theory, bacteria prefer to stick to hydrophobic – water-repelling – layers. Otherwise, they have to move water molecules on a surface aside, which costs a lot of energy,” Olga explains. The hydrogels retain a layer of water, fooling the bacteria.

“We started using the macroscopic hydrogel coatings but discovered they could only be applied to soft rubber surfaces. So, it could providea good strategy to target microbial attachment to rubber-based elements, likerubber-coated valves, but we wanted to look for a universal solution to prevent – or at least delay biofilm development. As an alternative, we selected nanogel-based coatings. Not only they offer all the advantages of hydrogels, but also their form of spherical nanosized particles makes them easily applicable as a coating.”

But of course, there are multiple challenges when translating the technology from one distinct field to another. Olga: “Drinking water bacteria are quite different from clinical strains. For instance, common organism used for testing the anti-adhesive coatings is a small round bacterium Staphylococcus aureus. To attach to the surface it depends on an uncoated site big enough to support its whole body. In drinking water, we have many more bacteria with a tail – a flagellum – that can attach to small imperfections in a coating as it is much thinner than a bacterium itself.”

Moreover, unlike in medical cases, these coating should withstand the critters  long term. “Drinking water pipes are installed for decades. Therefore, the coatings should remain stable and effective for extended periods of time. So, we performed a variety of tests lasting from 24 hours up to five weeks.”


And it worked. Depending on the bacteria tested, the nanogel layers repelled between 80 to 99% of the bugs. A unique feat with the mix of organisms never used for such test before. Olga: “It may take a long time before such coatings will be introduced to the drinking water sector, but we showed it that they are resilient against biofilms in representative circumstances. The goal of such application is to target water distribution sections that are the most prone to biofilm development – like in places of low flow or dead ends. And such coatings offer a great potential for small scale applications, such as drinking water end points like taps, hoses used in gardens or for cleaning industrial facilities, too. Nanogel coatings can ensure the safety of drinking water.”

The project is continued by another PhD candidate who focuses on long-term testing, and Olga now helps with its supervision as a part of her post-doc position. “At some point I had doubts if I will be able to finish this PhD, but I am proud I will. I hope to continue my work in a similar environment as here at Wetsus where industry meets research to respond to the increasing challenges we are and will be facing due to the climate change.”