Final report

Cleaning and Recycling of Residual Mixed Plastic Film

A proof of concept project for cleaning and recycling of residual mixed plastic film.

Project code: ISS001-001 Research date: Dec 2010-Mar 2011

Date: September 2011

WRAP helps individuals, businesses and local authorities to reduce waste and recycle more, making better use of resources and helping to tackle climate change.

Written by: Roger Evans & Edward Kosior

Front cover photography: Image of flexible mixed plastic residues at UK MSW facility WRAP, Imperial Innovations and Nextek believe the content of this report to be correct as at the date of writing. However, factors such as prices, levels of recycled content and regulatory requirements are subject to change and users of the report should check with their suppliers to confirm the current situation. In addition, care should be taken in using any of the cost information provided as it is based upon numerous project-specific assumptions (such as scale, location, tender context, etc.). The report does not claim to be exhaustive, nor does it claim to cover all relevant products and specifications available on the market. While steps have been taken to ensure accuracy, WRAP cannot accept responsibility or be held liable to any person for any loss or damage arising out of or in connection with this information being inaccurate, incomplete or misleading. It is the responsibility of the potential user of a material or product to consult with the supplier or manufacturer and ascertain whether a particular product will satisfy their specific requirements. The listing or featuring of a particular product or company does not constitute an endorsement by WRAP and WRAP cannot guarantee the performance of individual products or materials. This material is copyrighted. It may be reproduced free of charge subject to the material being accurate and not used in a misleading context. The source of the material must be identified and the copyright status acknowledged. This material must not be used to endorse or used to suggest WRAP’s endorsement of a commercial product or service. For more detail, please refer to WRAP’s Terms & Conditions on its web site: www.wrap.org.uk

Executive summary This project was commissioned as part of WRAP’s Research & Recycling Commercialisation Centre to investigate methods of recycling residual plastic films which are left over after passing through standard recycling configurations and are currently destined for landfill. The project successfully proved concepts of cleaning and reprocessing of residual mixed plastic film. Packaging films are used in vast quantities in the UK and appear at all stages of the recycling chain. Exact figures are available from the British Plastics Federation. In most recovery operations, multi polymer stream films are discarded as they have low value, or treated as a contaminant (for example where paper is the main product being recycled). This situation is even more prevalent where the films are heavily contaminated, as in residues produced from municipal solid waste (MSW). The project therefore looked at film residue material procured from 3 different sources: - Residual films from the Commercial & Industrial (C&I) stream collected via waste transfer station; - Residual post consumer films from a Materials Recycling Facility (MRF) processing dry recyclables; and - Residual post consumer films from a MRF handling black bag waste. In all instances, the format and general polymer composition of the film was photographed and analysed. As an average, the project found that 63% of all films examined were polyethelyne (PE) or polypropylene (PP) based and would be suitable for reprocessing if cleaned of contamination. All of the films identified were available at negative (gate fee based) or negligible (transport only) cost. All of the source materials at the time of the project were destined for landfill if moved within the UK. The project successfully identified and demonstrated all of the critical elements needed to construct a complete process which included size reduction, cleaning and extrusion techniques capable of utilising film from all three sources. The project subsequently succeeded in producing a commercially acceptable pelletised product with a sales value of £400 to £500 per tonne. The extruded pellet was then successfully evaluated as an input to 3 mm thick moulded products used in the UK at ratio of 100%. The end use rate would depend on the specific application given the flow behaviour and properties of the recovered material.

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Contents 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0

Introduction and Objectives ..............................................................................................................5 Definition and Project Scope .............................................................................................................5 Film from Commercial and Industrial Sources .....................................................................................5 Film sourced from MRF processing dry recyclables ..............................................................................7 Film from MRF processing “black bag” waste .................................................................................... 10 Size Reduction of Film .................................................................................................................... 12 Dry Cleaning of Film ...................................................................................................................... 15 Extrusion of Clean Film shred ......................................................................................................... 22 Characterisation of Extruded Pellet .................................................................................................. 23 Commercial Product and Markets .................................................................................................... 26 Next Steps and Recommendations .................................................................................................. 27

Figures Figure 1 Mixed film bales at North East Recycler ...........................................................................................6 Figure 2 Mixed film residues at Midlands Recycler .........................................................................................6 Figure 3 Hand sorting MRF residue stream ...................................................................................................7 Figure 4 HDPE sorted stream from MRF residue ............................................................................................8 Figure 5 Mixed Post Consumer Film stream from MRF residue ........................................................................8 Figure 6 Mixed Post Consumer Film (bags) from MRF residue .........................................................................9 Figure 7 Other rigid Mixed Plastics from MRF residue .....................................................................................9 Figure 8 UK MSW film residue ................................................................................................................... 11 Figure 9 UK MSW film residue colour mix ................................................................................................... 11 Figure 10 UK MSW 3D rigid plastic residue ................................................................................................. 11 Figure 11 Pierret “Robot” bale feeder ......................................................................................................... 13 Figure 12 C&I waste in bulk bags .............................................................................................................. 13 Figure 13 Pierret Robot automatic loading and positive feed ........................................................................ 13 Figure 14 Pierret auto guillotine first phase cutting...................................................................................... 14 Figure 15 Pierret process showing film after first guillotine, second cut and final conveying to big bag............. 15 Figure 16 Czech C&I film waste ................................................................................................................. 17 Figure 17 Czech Heavily contaminated C&I film .......................................................................................... 18 Figure 18 Czech Post consumer film .......................................................................................................... 18 Figure 19 Sorted Czech film fraction showing obvious similarities to UK waste source..................................... 19 Figure 20 Feeding post consumer film at the Czech Plant ............................................................................ 19 Figure 21 Feeding post Consumer with added contaminated C&I film ........................................................... 20 Figure 22 Post consumer and C&I film residue after first stage shredding ..................................................... 20 Figure 23 MAS DRD Dry Cleaning System ................................................................................................... 21 Figure 24 Shred before DRD cleaning ........................................................................................................ 21 Figure 25 Post Consumer Shred mix comparison after DRD at Czech Plant .................................................... 22 Figure 26 Clean Shred after DRD process ................................................................................................... 22 Figure 27 Pellets in production at Czech facility ........................................................................................... 23 Figure 28 Finished extruded pellet made from post consumer residual waste ................................................ 23 Figure 29 Image of Test bars moulded at 180C from post consumer film residue pellet produced at Czech ...... 24 Figure 30 Zwick testing machine with residual film sample on test ................................................................ 25 Figure 31 Demonstrating flexural strength of test bars ................................................................................ 25 Figure 32 Engineering stress curve of moulded samples .............................................................................. 26 Figure 33 Container joining plate moulded from post consumer film residue .................................................. 26

Tables Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 7

Analysis C&I sourced residual film ....................................................................................................7 Analysis of Total Residue Stream from Northern MRF ....................................................................... 10 Analysis of Film from sorted fraction of MRF Residue Stream ............................................................ 10 Analysis of MSW black bag residual materials .................................................................................. 12 Composition of Czech Input Materials………………………………………………………………………………………..….16 All sources material input analysis .................................................................................................. 17 Moisture level Results .................................................................................................................... 24

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1.0

Introduction and Objectives

Packaging films are used in vast quantities in the UK and appear at all stages of the recycling chain. A brief snapshot of the UK packaging industry (source British Plastics Federation) illustrates the scales involved: UK Plastics Packaging Industry - Profile Number of Converter Companies - 1,500 Number of Employees - 74,000 Tonnage - 1,600,000 tonnes Consumption per Capita - 27.2 Kg Sales Value - £2.75 billion 50% of Europe's food is packaged in Plastics A recent RAPRA project stated “Overall, the market for plastic film in Europe is around 5 million tonnes, of which 4.75 million tonnes are polyolefins”. Waste collectors and processors have a relaxed attitude to the collection and processing of film. For most, this waste stream is seen as a complication – difficult to collect, even more difficult to sort, with little or no commercial value to be seen at the end of the process. It is a major irritant to those who are geared to create revenue from paper streams. There is a lack of overall market for mixed films, providing little incentive for waste collection facilities to focus on more volume film recovery. This state of affairs is exacerbated when the film maybe in a variety of formats colours and polymers and is heavily contaminated. This is certainly the case with MSW generated films and residual films left over after the “good” films (mostly clear PE) have been removed at dry recyclable MRFs and C&I processors. The project therefore sought to demonstrate that viable processes exist for the conversion of these residual films, that the end product could be fit for several industrial applications while also being commercially acceptable. The proposed solution also needed to be economically viable and scalable to levels that will help to offset significant tonnages of plastic waste from landfill.

2.0

Definition and Project Scope

The project was commissioned by Imperial Innovations Commercialisation Services as part of the Proof of Concept (PoC) fund administered by the Recycling Research Commercialisation Centre. The project was given the title of “Cleaning and Recycling of Residual Mixed Film”. The scope of the project detailed key steps to be taken in 2 phases: Phase 1: Analyse polymer and contamination content from 3 different recyclers Establish usability criteria Commission trials of cleaning process and optimise process Deliverables: Characterisation analysis of residual streams & Interim report Phase 2: Commission extrusion trials & other processes to ensure product quality is achieved Supervise processing trials at each stage Characterise recyclate resin produced Supervise recyclate trials Deliverables: Characterisation of recyclate resin & Final Report The project scope does not include provision for full economic projections or sensitivity analysis of proposed manufacturing solutions subject to differing operational or market conditions. However, an indication of viability is provided in section 11 of this report.

3.0

Film from Commercial and Industrial Sources

Nextek approached a recycler based in Yorkshire and a recycling company based in the Midlands. Both companies take in C&I and Civic and Amenity (C&A) sourced waste which is generally presented to site in collection skips or loosely tipped. Both companies currently segregate clean polythene film, which for the most part is then baled and sold to export markets. Both have films which are either too dirty to sell on or are too mixed to be of any resale value.

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The project looked at the composition of the residual film and found a high polythene content, with a secondary and tertiary outer packaging (such as stretch wrap or pallet covers) being the predominant formats. The companies themselves keep few records regarding on-going composition of this residue, it is just classified as mixed plastic and the composition can change with each different skip that arrives – if they do get a revenue for it, it is usually just to cover transport costs. The material was invariably heavily contaminated with dirt, organics and moisture, with the worst offender being agricultural film which could have as much as 20% moisture and 15% contamination by weight. We therefore decided to concentrate on this type of material for the cleaning trials as the worst case scenario for Commercial & Industrial (C&I) films. (see section 5 dry cleaning of film). Sorting of this type of residue is generally deemed to difficult as some of the films are too contaminated or arrive in a format that makes it difficult to handle or shred. For automated sorting, the size would need to be reduced to ribbon size pieces or smaller. The project identified and demonstrated a robust technology for this (see section 4 size reduction of film) When quizzed about continuing volumes of this type of material, each company said that they could easily make 5,000 tonnes per year of mixed film available.

Figure 1 Mixed film bales at North East Recycler

Figure 2 Mixed Film residues at Midlands Recycler

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Table 1 Analysis C&I sourced residual film

Analysis C&I Sourced Residual film Contam Moisture HDPE 27%

Multi

PP

LDPE

4.0

HDPE

LDPE

PP

Multi

Moisture

Contam

C&I source one

23%

42%

15%

5%

10%

5%

C&I source two

31%

36%

11%

2%

12%

8%

Average

27%

39%

13%

4%

11%

7%

Film sourced from MRF processing dry recyclables

Nextek obtained access to a UK plastic recycler that handles the residual plastics stream from a MRF situated in the North of the country. For confidentiality the MRF did not want to be named, but the anecdotal evidence indicated that it was an authority run facility. The mixed plastics residue contained a variety of product, including the film not recovered by the MRF for recycling. In effect, this stream represented the MRFs out-throw plastic material and was available for zero cost. This residual stream was co-mingled with 3D shapes and even metals. The following images are of the residue after hand sorting into separate streams: Figure 3 Hand sorting MRF residue stream

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Figure 4 HDPE sorted stream from MRF residue

Figure 5 Mixed Post Consumer Film stream from MRF residue

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Figure 6 Mixed Post Consumer Film (bags) from MRF residue

Figure 7 Other rigid Mixed Plastics from MRF residue

Following hand sorting of one mill size bale (approximately 600 kilos weight) the film fraction was found to be 15% by weight, although obviously a lot more by volume. From this particular source, given that 15% would be film, there is 750 tonnes per year available. However, this stream also contains large fractions of valuable 3D polymers which if sorted, would make the recovery process more viable. The format analysis of the full stream was as follows:

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Table 2 Analysis of Total Residue Stream from Northern MRF

MRF "dry recyclable" residue

HDPE 3D 23%

PET 3D 33%

Film 15%

Mixed 3D 16%

Metal 5%

Moisture Contam 5% 3%

The residual film only fraction was also analysed with the following results recorded:

Table 3 Analysis of Film from sorted fraction of MRF Residue Stream

MRF source film residue

HDPE 16%

LDPE 48%

PP 15%

Multi 8%

Moisture Contam 8% 5%

Analysis of MRF Residual Film Source

Moisture 8%

Contam 5%

HDPE 16%

Multi 8%

PP 15% 5.0

LDPE 48%

Film from MRF processing “black bag” waste

The Project also looked at the worst case residues created by processors of black bag waste. In the past, virtually this entire stream produced in the UK has been sent to landfill as a comingled MSW derived waste. Nextek worked with a UK black bag waste processor who have created facilities designed to reclaim all valuable components (like metal) and convert organic materials to compost. In this way, they minimise the waste destined for landfill. Compost quality is severely affected by the presence of complex, inorganic materials, especially plastics, so the MSW facilities installed by this operator have installed Near Infra Red (NIR) sorting equipment to segregate as much plastic as possible. Once this is done, the plastic waste stream is further separated by air classification and ballistics into 2D (film) and 3D streams. Currently, there are few markets for the 3D stream as it is very contaminated and completely mixed, however, they are selling some to reprocessors at revenues around £80 per tonne. The 2D stream is currently all land filled at a cost of around -£75 per tonne including transport. This is a fairly low cost for the MSW operator as most of their facilities are situated on or adjacent to landfill sites. The “black bag” film stream is therefore very low cost, but has a high level of moisture and contamination. Nextek was able to visit a new UK site and analyse the film residue. It should be noted that at the designed throughput rate of this installation (10 tonnes plus per hour) a lot of non plastic items get through, especially in the film residue which had a high proportion of paper and textiles.

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Figure 8 UK MSW Film residue

Figure 9 UK MSW Film residue colour mix

Figure 10 UK MSW 3D rigid plastic residue

Nextek analysed the composition of the film fraction of the black bag residues with the following results:

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Table 4 Analysis of MSW black bag residual materials

HDPE 12%

Film residue MSW Black Bag

LDPE 35%

PP 18%

Multi 15%

Moisture Contam 10% 10%

Film from MSW black bag Analysis Contam 10% Moisture 10%

HDPE 12%

Multi 15% PP 18%

LDPE 35%

It should be noted that moisture content will vary during throughput, 10% is the estimated minimum level, but depending on a number of factors such as the season, the moisture level could be as high as 20%. The total polyolefin content of this residue was in excess of 65%, however, this survey has to be an estimate of consistent availability, given the variance from day to day, where contamination and moisture levels combined could be as much as 30% of the total residue. This UK MSW black bag business currently generate 3,000 tonnes of residual plastics from 2 sites in the UK and have 6 other sites in construction or planning stages. They estimate that residual film generated will be more than 15,000 tonnes per year by 2015.

6.0

Size Reduction of Film

Size reduction of film is an important step, as both the dry cleaning stage and automated sorting rely on a minimum size of particle to be effective. The fastest way of sorting film is with “whole item” NIR sorting, where a near infra red detector is placed over a conveyor belt and the item being looked for is diverted by a blast of air triggered by the NIR detector. If the film is in large pieces, it can mask other undesirable products or get entangled and therefore needs to be effectively size reduced before it is introduced into the system. This is especially relevant of the C&I type of waste, which can be dumped in part rolls, big bags or sheets. This is seen as a barrier to processing this material as a normal shredder will very quickly clog up and throughput will be dramatically reduced or stopped. Nextek have identified a robust cutting process which automatically feeds in bales of material and cuts film into definable sizes. The machinery is manufactured by Pierret in Belgium and they agreed to carry out a trial to demonstrate effectiveness with C&I waste.

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Figure 11 Pierret “Robot” bale feeder

Figure 12 C&I waste in bulk bags

The C&I film was contained in large polythene bags which were automatically lifted whole into the robot feeder shown. This applied a continual positive feed to the first Pierret cutting machine which was set to cut the film into 300mm sections.

Figure 13 Pierret Robot automatic loading and positive feed

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The Pierret cutting process is based around a guillotine set on a slightly elliptical trajectory. This ensures that materials are cleared immediately after cutting and that there is almost no chance for the material to jam. The process is extremely efficient for all types of flexible materials, but conversely cannot handle rigids very well. Although images shown are largely clear materials, the process works equally as well with contaminated residues.

Figure 14 Pierret auto guillotine first phase cutting

In order to obtain a regular size for most efficient NIR detection, a second Pierret guillotine was placed at right angles to the first line. This was then fed automatically by conveyor and the throughput speed matched to the input robot and first guillotine. The result was film throughputs in excess of 1 tonne per hour, cut into minimum 1500 x 200mm size, ideal for further processing via NIR detection. The throughput could easily be ramped up to more than 2 tonnes per hour by increasing the size of Pierret guillotines involved. The system is suitable for a pre-shredding, coarse cut operation. The film can then be fed in this format into a single shaft shredder to size reduce further (for example prior to extrusion) without the risk of jamming.

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Figure 15 Pierret process showing film after first guillotine, second cut and final conveying to big bag

Although it is extremely effective, especially with long length, bulky and difficult to handle films, this part of the process would not be essential for processing some of the residual waste film streams examined within this project, which have a reasonable “whole item” size or may have already passed through a pre-shredding process

7.0

Dry Cleaning of Film

All of the film streams identified were heavily contaminated with dirt, grime and moisture. Simply shredding or cutting the film into smaller pieces does not remove this contamination. Likewise, methods of separating films into basic polymer types such as NIR or specific gravity (sink float) does nothing to remove contamination or moisture. In fact, the sink float method adds to the problem by immersing the film in water. When film is processed without proper cleaning, the resultant flake will be very odorous and further processing will be difficult in all but the most forgiving (and therefore the lowest value) applications. The DRD cleaning process identified and demonstrated in this project removed moisture to the extent that the maximum moisture content found after dry cleaning was