Glass containers have been a great success and most glass packaging material is finding its way back to the glass industry. Leveraging on its expertise in the field, Wageningen Food & Biobased Research contributes to solutions which increase the recycling percentage even further.
The Netherlands has been separating glass from residual waste since the 1970s. For years the collection percentage fluctuated around 80%, a good result internationally speaking but still meaning that around 20% of glass ends up being incinerated. The Dutch government is aiming for a glass recycling percentage of at least 90% and one possible way to achieve this is mechanical recovery of glass from municipal solid waste (MSW). Wageningen Food & Biobased Research partnered with Nedvang, Attero and GRL to study the feasibility of this process.
Result of subsequent separation: 98.5% purity
To perform the technical analysis, 10,000 kilos of unsorted MSW was first sifted twice at the waste processing company Attero in Wijster. The household fraction was then subjected to a drum screen and windsifter at Busschers. Finally, the fraction was further sorted in the Ti-Tech research centre using two optical separators and an x-ray separator. The remaining concentrate of 150 kilos contained 1.3% plastic and 98.5% glass. In addition, no ‘undesirable’ glass was found, such as cullets from energy-saving light bulbs, ashtrays, ornamental objects and thermal glassware.
Scientist Ulphard Thoden van Velzen says that the analysis showed that mechanical recovery is technically feasible: “We proved that the remaining glass was sufficiently pure for reuse by the glass industry. The quality is even comparable to glass which has been separated at source. This means there are no technical objections to applying mechanical recovery to supplement glass containers. A similar result has yet to be achieved anywhere else in the world.”
Benefits vs. costs
Thoden van Velzen underlines that the analysis is based on a pilot and whether the results are as good in large scale tests needs to be seen in practice. He expects that the waste processing installation in Wijster can potentially recover 15 million kilos of glass a year. Question is whether the benefits of mechanical recovery are worth the costs. Thoden van Velzen: “Mechanical recovery contributes to the circular economy, but the costs are many times higher than separate collection at source. Hence it is up to the politicians to decide.”