Plastic Cup’s transmitter bottle has travelled 300 kilometres in 1 week

In addition to collecting, sorting, and processing floodplain waste, the Tisza Plastic Cup also studies plastic pollution in the river. If we know more about the behaviour of river waste, clean-up actions can become even more successful. On 7 January 2022, Plastic Cup river rescuer Krisztián Berberovics took advantage of the rising tide and released bottles equipped with GPS transmitters at two different locations.

“How fast do bottles travel on the flowing rivers, how far can they travel in a given time, and where, why and for how long do they get stuck?,” asked Plastic Cup scientific expert Miklós Gyalai-Korpos, listing the questions that transmitter bottles are expected to provide answer for.

The answer is far from obvious. While according to popular belief there is no reason to mark bottles as they will "float to sea anyway", Plastic Cup volunteers know from the bottle mails they have collected over the past ten years that this is not the case. But to convince the scientific community, the public, and the experts, it is not enough to refer to a decade-old Ukrainian message in a bottle found in a Hungarian floodplain, it requires thorough research. For two years, participants of the Zero Waste Tisza River project has been marking bottles using a variety of technologies. While the previous marking methods were more about overcoming technical challenges, the developments now ensure that data is collected continuously and reliably. Last time, two transmitter bottles were released on the river. The first one was thrown into the main current of Tisza river at Tivadar, and the other into the Bodrog river at Alsóberecki. They released from the bridge closest to the border in both cases, as this is the only way to drop the bottle into the main current during flooding. “Ever since the bottles are on their way, not a day goes by that I don't check where they are,” said Gergely Hankó, the man behind the idea of the marked bottles. “Their behaviour is very interesting and revealing, and we hope that they will confirm our hypothesis about river waste in the long term."

The Bodrog bottle didn’t get far; it stuck for days under Sárospatak, at a plastic dump well known to plastic pirates. It floated on eventually but got stuck in another floodplain. This is important data, as two other marked bottles got stuck in the same section of the river during last January's experiment. The data from the Clean Tisza Map confirms that floodplain pollution is even worse than average in these places.

Meanwhile, the Tisza bottle has been moving at breakneck speed, which can be followed in real time on the Zero Waste Tisza River project website, supported by The Coca-Cola Foundation. The GPS bottle made its way to Tokaj in one day, stayed longer in two places (above Tiszafüred and then at the entrance to Abádszalók bay), and after a week and about 300 kilometres, finally stopped at the Kisköre dam. The fact that it hasn't got through the dam proves that it is a real barrier protecting the lower reaches of the river from pollution. During floods, the Kisköre dam can hold up to 600 cubic metres, around 6,000 tonnes of waste.

Breakthrough after many failures

The bottle release in January 2022 was the third trial and the biggest success of the ongoing research and development process so far. The first plastic bottles released in May 2019 were equipped with radio telemetry transmitters, but these were soon lost: most of them were found by plastic pirates in the same year at Kisköre, just above the dam.

The second bottle release took place a year ago, with a completely different technology. Thanks to the development of Waterscope Zrt, the movement of the bottles could be tracked via an online map, but only for a short period of time due to unexpected technical difficulties.

At the request of the Plastic Cup, Waterscope Zrt. has further developed the special transmitters. The device works with a GPS satellite connection: every 15 minutes it turns on the GPS and measures the geographical coordinates. If the movement is longer than 200 metres, the new location of the bottle will appear on the tracking system map. Compared to the previous version, the most significant improvement – and the one that made the current success possible – lies in the device's energy management, which ensures that unexpected situations are handled in an energy-efficient way. After a week of operation, with temperatures sometimes well below zero, the batteries are working properly. The result of persistent development is a great technical solution that supports the work of the Plastic Cup. Tracking the movement of plastic waste in the river for such a long period is a significant achievement even on a global scale.

The Plastic Cup’s river waste mapping complements the hydrological research at the Budapest University of Technology and Economics as well. Researchers of the university are trying to model how the pollution spreads. The theoretical results can be compared with the practical learnings of the Plastic Cup, based on the movement of the transmitter bottles. This will allow better and more efficient waste tracking and validation for the modelling in the future.

It is heartening that the bottles making the longest journey were stopped by the Kisköre dam. The waste that accumulates here every year is collected and processed by the experts of the Central Tisza Water Management Directorate (KÖTIVIZIG) with the help of Plastic Cup volunteers. The work is made more comfortable by the Plastic Cup River Rescue Centre that opened last year.

Bottle mail from a kayak!

On 20 January 2022, the bottle that collected the most data so far was lifted from the waste field in Kisköre by the KÖTIVIZIG staff. After the device had been presented to the press, following a quick condition assessment and battery replacement, Attila Epres actor, kayaker, Plastic Cup volunteer and star of the web series "Plastic Kayaks", released the bottle again on the south, downstream side of the dam from a white-water kayak made of river plastic waste, so it could provide more useful data for the waste research. 

The sponsor of the Zero Waste Tisza project is The Coca-Cola Foundation, that provided financial support for the research, which made the technical development, testing and monitoring of the transmitter bottles possible.


Releasing the bottle at Tivadar:

Releasing the bottle at Alsóberecki: