Edwards Waste Paper of Barking, east London has pleaded guilty at the High Court to transporting waste to Brazil illegally.
Director Simon Edwards, 46, of Loughton and employee Jonathan Coombe, 41, from Romford admitted similar counts of exporting non-recyclable household waste.
Julio Da Costa, 51, and Juliano Da Costa, 27, from Swindon, Wiltshire are alleged to have arranged the shipment as they ran two companies that are now in liquidation.
In July 2009, the Brazilian government rejected 89 containers containing 15,000 tonnes of waste, which were then send back for inspection by the Environment Agency.
The maximum penalty for exporting waste illegally is an unlimited fine of up to two years in prison.