Six fire engines and around 40 firefighters were called to a fire at a plastic recycling centre in Coldharbour Lane, Rainham.
Part of a conveyor belt containing mixed plastic waste was damaged by fire. Fifteen members of staff left the building before the arrival of the Brigade.
The Brigade was called at 0811 and the fire was under control at 1025. Fire crews from Wennington, Barking, Dagenham, and East Ham fire stations attended the scene.
The cause of the fire is under investigation.