(Deng et al., 2019)

In theory, glass can be infinitely recycled in a closed loop but the majority of UK container glass waste is collected via mixed recycling streams, which results in some degree of unavoidable material contamination, so not all of the glass collected for recycling can succesfully be recycled back into glass.

The technology currently used to optically sort the colour of the glass and remove contaminants is only effective above a certain particle size (approximately 10mm).

Anythng below this size is considered unsuitable for remelt, comprised of an unknown mix of colours and containing too high a degree of CSP contamination (Ceramics, Stones and Porcelain)(WRAP, 2016). A study by Valpak with the input of British Glass in 2017 indicated that this loss rate on current glass recycling practices was 20.2% (Valpak, 2017).

The residual fraction of glass unsuitable for remelt is currently most often supplied to secondary processors who crush and grade the material for use as a sand / aggregate substitute.