An official investigation is under way after 160 containers of green bin waste from Ireland were stopped in Rotterdam en route to China because of contamination.

The failed shipments are estimated to have cost the waste industry in Ireland €500,000.

It has been claimed that contamination by customers is increasing; now accounting for 40% of green bin waste.

The 160 containers were stopped in Rotterdam en route to paper mills in China between October and December last year.

It is understood oxygen monitors revealed the presence of non-paper refuse.

Most of the shipments were returned to Ireland last month, while 51 were allowed to be reprocessed in The Netherlands.

Industry sources in Ireland say that the cost of processing green or dry mixed recyclable waste has increased by 30% because of contamination and that some sort of penalty system will be needed to stop people putting black bin rubbish into green bins.

Panda Recycling is to try out a new system in Dún Laoghaire where customers’ bins will be photographed while being emptied into trucks.

Those found to be dumping black bin waste will be first warned and then charged extra if the contamination persists.

Ultimately the company may refuse to service a particular customer.

The recyclable waste is sent to Materials Recovery Facilities (MRFs) in Ireland for sorting but not all contamination can be removed as it is said that customers go to the trouble of hiding waste in empty cereal boxes.

The National Trans-frontier Shipments Office, the body in charge of waste shipments, is investigating the returned shipments.

The Dublin City Council-run office says that the returned waste was incorrectly classified and that the contamination mainly involved the mixing of recyclables.

It is understood that the Department of Environment will be launching a public awareness campaign in the coming weeks to encourage waste segregation.

Last year the Government cancelled plans to introduce minimum charges for green bins as part of a pay-by-weight system and at present many waste customers do not have to pay for green bin collection.

Minister for the Environment Denis Naughten is expected to announce a new pricing structure for waste collection within two months.