Het regende en onweerde, maar dat mocht de pret niet drukken, afgelopen vrijdag tijdens de zesde editie van het TU Delft Zomerfestival. (Oud)-studenten en medewerkers van de TU konden op het terrein van Sport en Cultuur genieten van diverse acts.

‘Recycled Island’ is the name of the plastic island envisioned by Dutch architect, Ramon Knoester, of WHIM architects agency. He plans to filter out 44 million kilos of plastic waste from the North Pacific Gyre, which is the place situated between California and Japan where the ocean’s currents carry and amass pelagic debris. Knoester wants to turn this debris into 10,000 square kilometers of living space for half a million people. The waste will be sorted out, shredded, cleaned and heated, and from this floating elements will be made that can be bonded together to form an island.

Perhaps needless to say, investors for this project are yet to be found.“I’m trying to be as least skeptical as possible”, says Peter Berkhout, a plastic recycling expert at the faculty of Civil Engineering & Geosciences. He wonders what kind of business plan this project is based on.

“I expect that you would need high quality plastic. The elements need to be watertight and resistant to ultraviolet light, to name a few properties. But if you mix all kinds of different plastics and recycle them, you obtain very low quality plastic”, Berkhout explains. Sorting plastics is a big challenge. Together with colleagues, Berkhout is developing a system to sort out plastic bottle shreds. The process occurs in an opaque liquid containing iron oxide nano particles. A solution of iron oxide nanoparticles flows across a conveyor belt, below which a strong magnet is fitted. The nanoparticles closer to the magnet will be attracted more strongly, locally increasing the effective density of the liquid. This gives the liquid its separating capability. The higher the density of the scrap, the more it will sink into the liquid. In this way, the Delft researchers can sort polyethylene from polypropylene. However, sorting all kinds of plastics from the ocean is a different ball game altogether.

Dr. Gijsbert Korevaar (faculty of Applied Sciences), programme director of the MSc programme industrial ecology, posits another problem: “Most of the plastic is degraded and has turned into little particles that are hardy visible. Those particles, the size of plankton, are eaten by animals. They form most of the plastic mass.”

According to Korevaar, the ‘plastic soup’, as the gyre with high plastic concentration is also known, is not a stretch of ocean with floating plastic as far as the eye can see; rather, the plastic is spread out and much of it, especially the smaller particles, is suspended below the surface. “If Knoester would retrieve plastic from the ocean, the amount would just be the tip of the iceberg. But it would be great if he could do it and make some kind of big tangible construction out of it. It would be a statement generating more attention to this ecological problem.”