Factors affecting MF reject rates

Local Authorities (LAs) that collect dry recyclables as either a comingled or two stream collection send the mixed element to a MRF for sorting, and this is a key stage where rejects are identified.

LAs report on mixed recyclables sent to MRFs in questions 58 and 100 of Waste Data, the web based system for municipal waste data reporting by UK local authorities to government. These questions require information on end destination of the materials and information on reject. Rejected material can have an effect on recycling performance and may be identified and potentially removed at several points in the collection process. The maximum average percentage of reject in this study was 10.6% (average figure for England and Wales combined in 2015/16) which equates to nearly 361,000 tonnes.

Presently, the specific factors causing the high reject rates are unclear, as well as how much of this material could contribute to increased national recycling if rejects were removed or avoided. The following study aims to examine the potential factors that may affect reject, in order to help suggest areas to focus interventions on and also improve data quality. This is a short summary of the two phases of the study.