MRF material testing Dr Darren Perrin Consulting Group Manager Enviros Consulting

Testing material quality at MRFs - why? Input material Excessive contamination of inputs can affect the operation of a facility and the quality of outputs. Need to know how much and from where? Identify potential to target further materials Output material Poor or variable quality outputs can adversely affect end market acceptability and price per tonne (if not today, maybe tomorrow). Quality of outputs? Contamination? Cross-contamination of output products? Residual material Good quality materials can remain in the residual material

Co-mingled versus kerbside sort – potential to contaminate Co-mingled Contamination Kerbside Sort Materials Recovery Facility

Co-mingled contamination measurement points 1. Kerbside: % contaminated/rejected bins 2. MRF gate: % vehicle loads rejected 3. MRF ‘Input’ material: % contamination across input samples 4. MRF ‘Output’ products: % contamination of materials sold to end markets 5. MRF ‘Output’ residual: % non-target and % target material in ‘Residual’ stream

WRAP quality assessment projects  (2008) Practical field trials of material sorting and sampling techniques (Resource Futures, April 2008)  (ongoing) - Material quality assessment of municipal MRFs within England, Wales and Northern Ireland: awarded to Enviros, October 2008  (ongoing) - Material quality assessment of municipal MRFs within Scotland: awarded to Resource Futures, October 2008  (ongoing) - MRF output material quality thresholds: awarded to Resource Futures, October 2008

Sampling principles Good housekeeping  High quality accurate sorting  Calibrated scales  Accurate data recording Good sampling  A ‘sample’ should reflect as closely as possible the population as a whole  Control or represent where possible key determining factors  Sampling strategy: needs to consider practicalities (operational constraints) and coverage (across input sources, output streams/residue; through time)  Need to account for day-to-day and week-to-week variation (ideally also seasonal variation)

Sampling principles Statistical reliability  Is your data representative of what is actually happening?  95% confidence level, sampling error reduced with larger number of samples ~ for example, mean % non-target material from 100kg MRF input samples (MRF 001 results): 14.01% +/- 6.7% from 6 samples 13.17% +/- 4.01% from 15 samples 12.53% +/- 2.73%from 30 samples

Suggested sampling regime for key headline parameters No two MRFs will be the same: design your own sorting regime Review your results to adapt and calibrate Quality monitoring of your sampling regime Use quality monitoring to train sorting staff to sort more accurately and /or more efficiently

Indicative sample sizes and weights Material streamNumber of samples Minimum sample weight (kg) Input material4095 Output material News & PAMs4070 Mixed paper4070 Aluminium cans3025 Steel cans3040 Clear PET bottles3025 Mixed plastic5030 Natural HDPE containers3025 Residual material1030

Sampling points Input material ‘Residual’ material Hopper Magnet Eddie current News & PAMs Mixed paper and card Ferrous Non-ferrous PET Mixed plastic Conveyor Chute (enclosed?) Baler/ pile Manual pick Baler/ pile Manual pick Baler/ pile Manual pick Baler/ pile

Mass flow approach Tonnes paper in (x) Tonnes out in other product streams and residual (z) Tonnes out as product (y) Process x = y + z z = x – y y = x - z

Potential to target wider range of materials? Mass flow approach to focus the issue:  Which non-target materials significant?  Which of value to end markets?  Do technologies exist to capture?  Potential to improve resultant quality?

Input and output compositions: WRAP field trials

WRAP projects: overview 31 MRFs (22 England, 4 Scotland, 2 Northern Ireland, 3 Wales) Data to cross-reference quality across different MRFs Over 5,300 samples being sorted into 16 material categories (estimated 285 tonnes of material) Fieldwork November March 2009 Range of MRF types: – 12 x training MRFs (1-3 day training, ongoing support) – 9 x full sort MRFs (1-2 weeks sampling) –10 x data MRFs (MRF process data review) Mass flow assessment i.e. input, output and residual samples sorted

Concluding remarks  Sampling material quality at MRFs is an essential part of understanding quality and marketability of MRF output materials  It can be undertaken in a systematic and resource efficient manner  The ongoing WRAP material quality studies will provide data which will inform material quality issues across the UK  Important to take mass balance approach - Pin-point actions to raise output quality - Consider potential to target new materials

Dr Darren Perrin Consulting Group Manager Enviros Consulting Thank you For further information on sampling please contact WRAP in the first instance.