From 1 July 2019 it will be prohibited to distribute and use disposable plastic products during events in the public space.
The ban on single-use plastic products must drastically reduce the volume of waste in Brussels and contribute to a cleaner public space. Disposable plastic products include: straws, trays and packaging for all kinds of food, packaging to consume food on the spot or to take food with you, disposable cutlery, stirrers, cups.
Street trading is not covered by this regulation, with the exception of street trading activities near an event organized by others in the public space.
A fine or an administrative sanction can be imposed in the event of an infringement of these regulations, in accordance with the law of 24 June 2013 on municipal administrative sanctions.
More info here