Bas Emaus (22) wants to purify water with algae: 'We can solve the nitrogen crisis 2.0'

With algae balls that filter pollution, 22-year-old Bas Emaus wants to save water quality in the Netherlands. He won the title 'Most Innovative Student in the Netherlands' with it last week. 'We are turning a green enemy into a green ally.'

Bas Emaus during his pitch at Holland's Most Innovative Student 2025. | Credits: Jesse Wensing

Forty seconds left. Bas Emaus looks bewildered at the clock during the finals of the Netherlands' Most Innovative Student. For weeks, he practiced his three-minute pitch. Each time he came out exactly on time, sometimes even slightly late. But now, at the moment it really counts, he finishes well within time. 'I thought: shit, did I miss something important?'

The 22-year-old former biomedical sciences student at HAN - he graduated in July - hadn't missed anything. On the contrary. A few hours later it was announced at Cleantech Park Arnhem that he and his company JiTiBa Algae Technologies were one of the winners.

"It was really mega exciting," Emaus says on the phone a day later. He has been in front of large audiences before, but this was different. 'When it's competitive, it's a whole different kind of excitement.'

As a prize, he gets to join a Dutch trade mission to Silicon Valley in 2026. But more importantly, the win is recognition that his solution to one of the Netherlands' biggest environmental problems is being taken seriously.

Green enemy as ally

What Emaus is doing with his company JiTiBa sounds simple: purifying water with algae. But how he does it is new. He puts micro-algae into gel balls - similar to the tapioca balls in bubble tea, but green. He puts those little balls in the water coming out of sewage treatment plants before it flows back into rivers and streams. The algae eat the pollution: nitrogen, phosphates, heavy metals.

"We are turning a green enemy into a green ally," says Emaus. Because normally, algae are precisely a sign of pollution. In summer, rivers turn green because of blue-green algae, a problem caused by too many nutrients in the water. Emaus uses the same algae, but under controlled conditions.

The fascination with algae began three years ago. For his education, Emaus traveled daily by train to Nijmegen. 'Every day I went by train across the river Waal. And every summer I saw the river get greener and greener. Sometimes just really dark green.'

That was exactly the time when the nitrogen crisis was in the news. When he saw the algae growing on the pollution in the river, he had a hunch: why not use these natural purifiers instead of fighting them?'