Appendix III explanatory information regarding contamination, reject and – residue rates Not all material that enters the PI MRFs is target material (i.e. paper, card, cans, plastic bottles). There is also non-target material that residents have incorrectly placed into recycling bins these items have to be rejected from the stream, mostly by manual means. In addition, – at the end of the sorting process there will be material which has not been “process residue” – separated into a clean waste stream and which is sent for disposal. Together these and “reject” make up This is highlighted in the diagram below. “process residue” streams “MRF Residue.” Source of MRF residue: The MRF residue rate is the proportion of MRF inputs that are not sent to market as a recyclable product. The residue rate is a different measure to the contamination rate. In order to measure performance and allocate income from sale of material, it is necessary to sample inputs to the MRF from each WCA in order to gauge the level of non-target material being delivered within DMR. Samples are taken from the point at which a WCA delivers DMR (i.e. it could be a waste transfer station or at the MRF itself if a WCA is delivering material directly). The analysis, carried out through the Materials Analysis Facility (MAF) calculates a contamination rate for each authority. Table 4 below highlights key differences between the contamination rate and MRF residue rate, and explains how the residue rate will inevitably be higher than the contamination rate.
Appendix III – explanatory information regarding contamination, reject and residue rates Not all material that enters the PI MRFs is target material (i.e. paper, card, cans, plastic bottles). There is also non-target material that residents have incorrectly placed into recycling bins – these items have to be rejected from the stream, mostly by manual means. In addition, at the end of the sorting process there will be “process residue” – material which has not been separated into a clean waste stream and which is sent for disposal. Together these “reject” and “process residue” streams make up “MRF Residue.” This is highlighted in the diagram below. Source of MRF residue: The MRF residue rate is the proportion of MRF inputs that are not sent to market as a recyclable product. The residue rate is a different measure to the contamination rate. In order to measure performance and allocate income from sale of material, it is necessary to sample inputs to the MRF from each WCA in order to gauge the level of non-target material being delivered within DMR. Samples are taken from the point at which a WCA delivers DMR (i.e. it could be a waste transfer station or at the MRF itself if a WCA is delivering material directly). The analysis, carried out through the Materials Analysis Facility (MAF) calculates a contamination rate for each authority. Table 4 below highlights key differences between the contamination rate and MRF residue rate, and explains how the residue rate will inevitably be higher than the contamination rate.
PIPerformance2017-18.docx