I have asked Epson support, here is the answer:
"As the bottles do not have a chip, they can be disposed of as normal in household waste. There is no separate recycling process for this. "
I would also like to point out Epson's recycling programme:
https://www.epson.eu/viewcon...
Almost all components can be recycled, e.g. the ink cartridges can be returned free of charge. But these ink bottles in particular are unfortunately just plastic waste.