materials recycling facilities _specifications, operations & costs _key studies wrap2003

8/14/2019 Materials recycling facilities _specifications, operations & costs _key studies WRAP2003

1/20

Local authority recycling

Recovering value rom MRFs

A review o key studies relating to the specication,operation and costs o Materials Recovery Facilities


2/20


3/20

Foreword

The UK is changing undamentally the way it deals with its waste.From very low levels in 2000, recycling o waste has grown strongly

and now stands at 27% or household waste in England and perhapssomething over 50% or commercial and industrial waste. This change

brings signicant environmental benets: in reducing the need toextract raw materials and in reducing climate changing carbon

emissions by an estimated 10-15 million tonnes a year; equivalent totaking 3.5 million cars o the road.

The change has not been eortless. Local collection systems, sorting

and reprocessing capacity as well as the end markets or materialshave all had to adjust to these new demands with some parts o the

system being more responsive than others. As the Government isreviewing its waste strategy or England and signalling that a urther

signicant expansion in recycling will be needed, WRAP has beenreviewing key parts o the recycling system to identiy areas that will

need urther attention to maximizing the benets rom increasedrecycling levels.

Materials recovery acilities (MRFs) are increasingly important inproviding quality raw materials to industry. MRF capacity in the UK

is growing but it is unevenly distributed and investment in urthercapacity will be needed as demand grows.

In most cases, MRFs are designed to separate co-mingled recyclables1

into their individual material streams and prepare them or sale intothe commodity markets. Although ew local authorities are likely to

operate MRFs themselves, they will be involved in procuring servicesrom private contractors that involve the design, commissioning and

operation o MRFs. Understanding all stages rom collection through

sorting and bulking to the sale o recovered materials will ensure that,prior to embarking on the procurement route and preparing servicespecications, local authorities are better inormed about the cost

implications o alternative options.

This summary document draws together the results o recent studiescommissioned by WRAP and draws on good practice in MRF design

and management rom the USA and Europe. It is intended as anintroduction or those unamiliar with the issues surrounding the

specication, operation and costs o MRFs.

Understanding MRFs 1

1. Around one third o English local authorities collect recyclable materials co-mingled but this number is expected toincrease as recycling programmes expand. Most o the remaining authorities operate kerbside sort schemes whereby

materials are separated at the kerbside into their individual material streams. Collections are made using stillage ormulti-compartment vehicles thereby avoiding the need or sorting o materials at MRFs.


4/20


This summary document draws together the results o three separatestudies commissioned by WRAP:

MRF Case Study Review (contractor: The Dougherty Group LLC), which

looked at material sorting practices and technologies employed at across-section o MRFs in England, the USA and Europe;

MRF Cost Model and User Guide (contractor: Entec Consulting Ltd),which developed a costing tool or dierent materials sortingoptions; and

Contractual Arrangements between Local Authorities and MRFOperators (contractor: AEA Technology plc), which reviewed and

assessed existing contractual relationships between MRF operatorsand local authorities across the UK.

It presents an overview o key aspects in the specication, operation

and costs o MRFs with specic reerence to:

principles o MRF operations;

the main steps involved in processing recyclables;

costs and economy o scale benets; and

contractual arrangements to support investment and promote

high standards o operation.

It is intended as an introduction or those unamiliar with the issuessurrounding the specication, operation and costs o MRFs. The ull

reports are available on WRAPs website www.wrap.org.uk. The CostModel is available on request.

Introduction


5/20


Receiving materials

It should be standard practice at a MRF or incoming recyclables tobe received and stored, prior to processing, on a tipping foor which is

protected rom the weather. Water can signicantly reduce the value osome recyclables especially paper and card. There should be sucient

capacity to store at least two days worth o incoming materials. Thiswill enable collection rounds to continue even during unscheduled

equipment downtime and at times o high demand such as the post-Christmas period. It also gives the MRF a buer so that it does not

have to orce material through the MRF aster than its design allowsor, which can have adverse consequences or quality.

Pre-sorting

Inclusion o an adequate pre-sort station in a MRF can deliver qualitycontrol and eciency benets. Pre-sorting not only allows removal o

contaminants early in the sorting process, but also permits removal

o specic recyclables that might otherwise hinder sorting activitiesdownstream. Materials such as lm plastic, oversized cardboardas well as non-recyclables (organics, wire, wood etc) can cause

problems or some o the automated processing equipment, andcan be removed at the pre-sort stage. This enables the processing

equipment to operate as designed and makes manual sorting moreecient. Although pre-sort stations are common in North American

and European MRFs, they are not incorporated in all MRFs in the UK.

Managing fows

Ecient sorting critically depends on a continuous and even fow omaterial being maintained through the MRF. Levelling out the fow

o material occurs as the materials enter the sorting process. Thiscan be achieved by using a series o conveyors operating at variable

speeds, stationary gates or metering drums.

MRF operations

There should be sucient capacityto store at least two days worth oincoming materials.

The tipping foor at a MRF. Incoming materials are

received and stored here prior to processing.


6/20


Separating bre rom containers

In a MRF accepting ully co-mingled materials, one o the rstprocessing steps involves separating bre streams (i.e. paper, card,

cardboard) rom container streams (i.e. cans, plastic bottles, glassbottles/jars). A trommel screen typically is used or this purpose in

the UK. In North America disc screens are more common. Dependingon the size o the MRF, several stages o screening may be involved.

The overall aim is to enable separate bre and container streams toundergo appropriate sorting.

Sorting bre

To meet market specications, bre needs to be sorted into its

various grades. Typically, MRFs in the UK sort three grades o paper:OCC (old corrugated cardboard), news & pams (periodicals and

magazines), and mixed paper. Some MRFs only sort into OCC andmixed paper whilst some MRFs in North America sort into six grades.

Sorting can be done (i) manually, (ii) using disc screens or (iii) usingmore advanced optical scanners. Smaller MRFs tend to rely onmanual sorting, while larger acilities use disc-screens. The use

o optical scanners is relatively new and, due to high capital cost,generally conned to high-throughput MRFs.

MRFs that negatively sort paper (i.e. allow it to run o the end o theconveyor belt ater other materials should have been extracted) have

experienced quality-related problems when the materials have beenshipped to UK paper mills. In some cases, loads that do not meet UK

mill specications are shipped overseas or recycling.

The quality standards set in the UK do not have the clarity o thespecications used in some other countries. MRFs in the UK

requently appear to be guided by rather broad specications (e.g.


7/20


Sorting can be donemanually, using discscreens or using moreadvanced opticalscanners.

paper

specifcations

should be well

publicised

where this is not already done, paper specications shouldbe (i) well publicised and (ii) available on paper mills andreprocessors websites so that all potential suppliers have

access to them;

implement testing procedures to determine quality o materialsreceived at mills. Whilst this is undertaken at several UK mills,

there is no standard testing procedure. The adoption o similarprocedures across the sector could improve the quality o

materials received and potentially allow the development o aprice dierential in avour o good quality materials; and

a continuous eedback system, advising MRFs o the qualityo materials received during any given month, should be

implemented. Results o random tests can be emailed to theMRF, enabling a quick response by the MRF manager in cases

where the quality o a shipment is not consistent with that oprevious shipments.

The system or developing acceptable standards or supplying paperto UK paper mills appears to be based on bilateral arrangements

between individual MRFs and individual mills.

The ollowing steps are thereore recommended:


8/20


Sorting glass containers

Only a limited number o UK MRFs that process co-mingled dryrecyclables accept (container) glass as part o the incoming stream.

Where glass is collected at kerbside, this is mostly carried out usingkerbside sort systems which keep the glass separate rom the paper

and other materials. However, several o the newer MRFs in the UKare accepting glass and it is possible that collection cost pressures will

encourage more local authorities to consider including glass in co-mingled collections.

Most co-mingled MRFs in North America process glass, believing

that it can be eectively separated rom paper using multiple discscreens. The paper is shipped to pulp mills and glass is sent to glass

container manuacturers. This approach is not accepted by UK papermills who are concerned that the quality o paper coming out o MRFs

is not meeting their needs. Glass contamination o the paper stream,in particular, is considered to be a signicant business risk. As a result

the majority o paper sorted at MRFs where glass is part o the incomingmaterials is exported.

Where glass is handled in MRFs it is relatively easy to separate rom

other containers (e.g. plastic bottles and cans) because o the densitydierences o the materials; an air classier can be used to separate

most o the glass rom the plastics and cans.

Although there are signicant price dierentials or clear, amber andmixed glass, refecting the dierent supply and demand or each o

these materials, colour sorting o glass does not take place in any UKMRF. The majority o the glass recovered goes to aggregates markets.

Colour sorting capacity, however, is being installed by the majorcontainer glass reprocessors. The decision on whether colour sorting

o glass is viable rom an economic viewpoint is being made on a case bycase basis by the MRF operator.


9/20


Sorting metal containers

Technologies capable o separating steel (i.e. errous) and aluminium(i.e. non-errous) cans rom other containers are reliable and

common. Overband magnets and magnetic head pulleys in conveyorswill readily separate errous cans, while eddy current separators are

typically used to sort aluminium cans. In view o the high value o (andstringent specications or) aluminium, manual quality control should

be employed ollowing sorting and beore baling to ensure the productmeets market requirements.

Sorting plastic containers

A signicant challenge or UK MRFs will be increasing their capacityto sort plastics into a wider range o polymers. Currently, many

local authorities in the UK restrict plastic collections to bottles only.The limited capacity currently available to sort mixed plastics is

a constraint on recycling much domestic plastic waste especially

packaging. It is also a actor in the UKs current reliance on exportmarkets or mixed household plastics.

In a MRF, plastics are sorted by resin (typically HDPE and PET) usingboth manual and automated techniques. Manual sorting by resin is

most prevalent, however ecient automated sorting is carried outprimarily through use o optical scanners. Optical systems can beused to sort multiple grades o plastic, but are more costly to install

and need high volumes to justiy their costs.


10/20

Baling and shipping

Decisions on whether or not to bale materials processed at a MRFmust take into account market requirements, market prices and

the dierence in the cost o transporting materials baled or loose.Although most materials processed at a MRF are baled beore

shipment to market, many MRFs in this country deliver paper loose(i.e. not baled) to UK markets/ paper mills.

A baler tends to be the single most important piece o equipment in a

MRF. When selecting a baler, the key is to ensure that it will providesucient baling capacity, as well as produce bales that meet market

requirements in terms o size, density and weight. I there is onlyone baler and it becomes disabled, the entire sorting process can be

compromised. It is thereore advisable to consider investing in back-uparrangements which might be access to another baler or appropriate

on site storage acilities.

As an alternative to baling, materials (particularly cans) can be

crushed and loaded loose or transportation to a merchant orprocessing acility.

Just as incoming materials need a covered tipping foor which is largeenough to cope with breakdowns and delays, so there needs to be

adequate storage or sorted materials including covered storage ormaterials which can deteriorate in quality, or example, paper.


Bailed aluminium cans.


11/20


Managing residues

Residues rom a MRF consist o (i) non-recyclables (i.e. contaminants)that are mixed in with the targeted recyclables delivered to the MRF

and (ii) recyclables that are not sorted during processing. Residues areexpensive to collect, process and dispose o, so MRF operators should

strive to minimise them. This can be achieved by:

auditing incoming recyclables to identiy levels and types ocontamination and providing regular eedback so that local

authorities can take action;

working directly with collection authorities to reduce

contamination levels in incoming materials;

applying dierential gate ees to reward local authorities

whose collections contain low levels o contamination;

conducting residue audits to identiy quantities o missed

recyclables, and then working to improve processingeciencies; and

putting residues into the sorting system or a second time to

ensure that all recyclable materials are taken out.


12/20


MRF Cost Model

As a result o work to establish the typical costs involved in settingup and operating a MRF, a costing tool has been developed and is

available, on request, rom WRAP. The MRF Cost Model providesrepresentative capital and operating costs or a range o MRF sizes.

Specically, it gives the user the chance to tailor several speciedMRF designs to local conditions and to determine sorting costs

resulting rom:

specic MRF design parameters (e.g. capacity o the tipping

foor and product storage areas);

operating conditions (hours, shits, days per week etc);

decisions on whether incoming recyclables are to be ullyco-mingled or two stream;

whether they are to be bagged or loose, and whether or not

glass is to be included;

designation o which materials are to be manually sorted;

designation o which materials are to be baled;

labour rates or operating and supervisory sta;

designation o recovery rates or targeted recyclables;

shipping costs or materials to be marketed and revenue rom

the sale o materials; and

baling wire costs, disposal ees or residue disposal, charges

or electricity consumption, the unit cost o constructing the

MRF building etc.

Costs


13/20


By changing these variables, the user can assess the impact onoverall costs. The user is thereore able to identiy, or a MRF o a

particular capacity:

the cost o a two-stream2 and a ully co-mingled sorting system;

the cost o adding glass to the incoming recyclables stream; and

the additional costs associated with processing bagged recyclablesat a ully co-mingled MRF.

These alternatives can be investigated not only or a wide range o

operating parameters but also in the context o a range o options ormarketing the sorted materials.

I used in conjunction with the Kerbside Analysis Tool (KAT also

available rom WRAP), the MRF Cost Model will enable localauthorities to understand the total costs o managing the collection,

bulking and sorting o dry recyclables and to compare the relativecosts o dierent systems.

Materials included within the MRF Cost Model as targeted materials

(i.e. those designated by local authorities as ocially part o theircollection schemes and which householders are asked to recycle)

include:

Fibre: news and pams, magazines, directories and catalogues,recyclable paper, paper and card packaging, cardboard; and

Containers: errous ood and beverage containers, errous aerosolcans, aluminium ood and beverage containers, aluminium aerosol

cans, glass bottles/jars (clear, green and brown), all plastic bottles.

Most o the incoming recyclables are assumed to originate rom alocal authority recycling programme, including materials collected

through kerbside, estate and bring sites. The recovery rates refect agood practice standard that local authorities are likely to aspire to

over the next ve years as recycling programmes expand.

The MRF Cost Modelprovides representativecapital and operatingcosts or a range oMRF sizes.

2. Some MRFs are designed to accept incoming materials in two streams. In some cases fbre is kept separate

rom containers (glass, plastics, cans) at the point o collection; in other schemes glass is kept separate rom theother materials.

10

Additional processing costs per

tonne at ull capacity can range

rom 6 - 10.

6


14/20


Cost implications

A sample cost curve or MRF operations has been derived rom the MRFCost Model and is presented below. This shows the variation in the unit

cost per tonne or MRFs o dierent design capacities. It shows that theunit cost per tonne begins to level out at higher throughput tonnages

(80,000 100,000 tpa) but rises signicantly at lower throughputtonnages. In the example given the cost o an 80,000 tonnes per year

acility operating at ull capacity is 40 per tonne, compared to 80 pertonne or a 40,000 tonnes per annum acility.

The cost curve also shows the cost implications o operating a MRF

at 50% capacity (i.e. on a single-shit) compared to ull capacity (i.e.a two-shit basis). The lower o the two cost curves applies when a

MRF is operating at ull design capacity. Any reduction in throughputtonnage below that level increases the unit cost o processing. For

a acility with a design capacity o 80,000 tonnes per year, the costdierential between operating at ull capacity and 50% capacity is

almost 20 per tonne. MRFs operating at above design capacity riskailing to meet quality standards.

MRFs operating atabove design capacityrisk ailing to meetquality standards.

Fully co-mingled MRF cost per tonne.

200

180

160

140

120

100

80

60

40

20

0

Tonnes/yr

Cost/Tonnesin

s

50% Capacity

Full Capacity

MRF Gross Costs

10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 90,000


15/20


As a result o the work underpinning the development o the modelsome broad conclusions can be drawn regarding the sizing o MRFs

and the opportunities to achieve economies o scale.

Processing higher tonnages can be economically advantageousThe MRF cost model suggests that MRFs below an annual

capacity o 80-100,000 tonnes will not achieve optimal operating

costs. Facilities o this scale are needed to achieve economieso scale but also to justiy investment in more automated andsophisticated sorting equipment that will help maximise the value

o the recovered materials. By sorting incoming materials intomore categories, the value o these materials can be increased.

Historically UK MRFs have tended to be smaller (less than 50,000tonnes per annum) although new capacity is being planned at this

size or signicantly greater.

Processing costs at a fully co-mingled MRF are higher than thoseat a two- stream MRF of the same size

At a ully co-mingled MRF, more sorting is required to separate out

dierent recyclable materials. For the example acilities includedin the cost model, the additional gross processing costs range rom6 per tonne (at an annual throughput o 85,000 tonnes) to 23 per

tonne (at an annual throughput o 10,000 tonnes).


16/20


Contractual relationships between MRF operators andlocal authorities

There are a number o possible rameworks within which MRFs can

operate. They include the ollowing, the rst o which is by ar the mostprevalent in the UK:

In some cases in the UK, ormal contractual agreements are not in

place between local authorities and the MRFs they use.

Irrespective o the precise nature o the agreements, all partiesinvolved in operating a recycling system must work together closely,

with each carrying out its responsibilities eciently in order or the

others and the system as a whole to succeed.

Contractual arrangements

To maintain competitionand cost transparency,local authorities maydecide to tender sortingand collection unctionsseparately, where this isappropriate.

a MRF operator sorts materials rom local authority collection

schemes and charges the local authorities a gate ee;

a private contractor collects the materials (under contract tothe local authority) and that same company operates the MRF

and charges the local authority(s) or collection and sorting;

a local authority owns and operates its own MRF;

a local authority owns and operates its own MRF and acceptsmaterials rom other local authority schemes (typically

charging a gate ee);

a local authority owns the MRF and contracts the operation toa private contractor; and

a consortium o local authorities own the MRF and contractthe operation to a private contractor.


17/20


Saeguarding and improving perormance

Contractual arrangements can be ramed in ways that incentivisegood perormance and can incorporate mechanisms or monitoring

contract perormance. In the UK some contractual arrangements donot include incentives or perormance criteria to increase recovery

rates and achieve required quality standards; perormance standardswere ound to be more common in Europe and North America.

The advantage o incentives and monitoring mechanisms is that they

enable the relevant parties to be clear about the extent to which theyare carrying out their responsibilities eciently and also highlight

specic areas where eorts to improve perormance may be targeted.

When drawing up and managing contracts, options and issues toconsider include the ollowing:

Perormance-based contracts

Local authorities can stipulate perormance levels to be achieved bythe company contracted to carry out the sorting process. Perormanceindicators can include vehicle turn-round times, availability

requirements, material quality, material rejection rates, residue rate,market prices achieved, overall recovery rate, etc.

Identifcation o materials to be sorted

To ensure the success o kerbside recycling programmes, localauthorities should determine the materials to be included in

collections. Individual companies can then be invited to submit bids orsorting the materials collected, outlining costs that will be incurred

and revenues that will be generated. To maintain competition andcost transparency, local authorities may decide to tender sorting and

collection unctions separately, where this is appropriate.

Processing efciency and permissible residues

Contracts with MRFs should speciy an acceptable maximum level oprocess residue. Ecient MRFs appear to operate within the range 2%

to 5% residue. Processing eciency targets can thereore be based onthe percentage o input material processed, with nancial deductions

and bonuses or perormance below or above the agreed eciencyrate; alternatively, an excess charge (e.g. 90 per tonne as in one

example identied) could be made or materials rejected during theprocessing phase.


18/20


Establishing sorting costs and revenues

Tenders and contracts or the sorting o kerbside materials shouldstipulate the cost per tonne o sorting the specied materials, the

minimum revenue to be generated rom the sale o sorted materials,and a plan or returning part o the revenue to the local authority, to

help oset the direct costs o collecting the materials. Achieving top

price or sorted materials is thereore an important requirement.

Typically, it is the responsibility o the MRF operator to secure

markets or recovered materials. As well as stating anticipated pricesor sorted materials, the contract should have a mechanism or

varying prices rom time to time in line with market fuctuations.

Where local authorities retain income rom the sale o materials, thisincome may be reinvested in the service to reduce the gate ee paid

or oset the costs o collection, giving the local authority an incentiveto maximise the quality o the recyclables it collects. However, a

reduction in gate ee may mean that the MRF operator would not

benet rom the additional income generated and might not beincentivised to obtain the best price or recovered materials.

Where these are in place, revenue-sharing arrangements betweenlocal authorities and MRF operators typically involve a 50/50 split.

Clearly, where revenue is shared between all parties involved inthe operation, there is an incentive to maximise quality in both the

collection and the processing o recyclable materials.

Visual inspection and random sampling

MRF operators generally visually inspect incoming loads or

contamination. Where the specied contamination limits are exceeded,loads may be rejected with the cost incurred by the local authority,

thus providing an incentive or that authority to manage the quality othe materials collected.

Random sampling rom collection trucks to check or contamination

should be conducted by the MRF on a monthly basis, with the resultingaudit reports orwarded to the local authority and/or the collection

contractor within a day or two.

Moving sorted items or transport.


19/20


These studies have raised a number o issues related to thespecication, operation and costs o MRFs. In particular they

emphasise the importance o MRFs producing consistently highquality materials. The implications o MRFs not achieving this is

that materials are oered to the market that do not meet the qualityspecications required by UK reprocessors and possibly, as a result,

lead to more materials being exported.WRAP believes there is a role or more MRF capacity in the UK, butthis capacity needs to be o the right sort, be in the right place and

be capable o delivering quality materials that meet endmarket requirements.

In terms o the right location a balance needs to be struck betweenachieving the economies o scale oered by larger acilities and the

potentially higher transportation costs associated with deliveringmaterials to larger, more centralised MRFs. Many o the larger

metropolitan areas will produce the required volumes o materialallowing larger acilities to be situated close to the collection areas.

For semi-urban and rural areas, the costs o running a numbero smaller, local acilities need to be compared with the higher

transportation costs but potentially lower unit costs o sorting atlarger acilities. When considering the latter option, it is essential to

ensure that it represents a satisactory solution in terms o balancingcosts, eciency and environmental impact. The MRF cost model and

other costing tools provided by WRAP can help inorm such decisions.

WRAP is undertaking urther work to better understand thecharacteristics o current MRF capacity and where additional capacity

is most likely to be required in the uture.

One challenge to be addressed, especially in two tier local governmentareas, is or decisions on recycling services to be made in the light o

the ull cost o the service i.e. collection and sorting costs and not onsorting or collection costs alone.

In terms o the right sort o capacity WRAP believes that MRFs

should develop as value actories, ensuring that maximum valueis obtained rom the recovered materials both through sorting and

preparing these materials ready or use by reprocessors.

Conclusions

This will require acilities that:

are appropriately sized;

adopt appropriate sorting technology;

are integrated with collection

systems and able to handlematerials rom a number ocollection schemes. MRFs can be

designed to process ully co-mingledhousehold recyclables alongside

more segregated streams by usingseparate in-eed lines;

have good quality control andeedback systems;

have committed management andtrained sta; and

eective regulation.

It will also require:

contractual or other arrangementsthat incentivise those that send

materials to MRFs, to take an interestin the standards that are achieved;

contractual or other arrangements

that incentivise MRF operatorsto lower unit costs o sorting and

increase the revenue rom the sale othe processed materials; and

clearer quality standards orrecovered materials, particularly

paper, and the adoption o standardtesting procedures to determine

quality o materials received at mills

rom MRFs.


20/20

www.wrap.org/materials

Waste & ResourcesAction Programme

The Old Academy21 Horse FairBanbury, OxonOX16 0AH

Tel: 01295 819 900Fax: 01295 819 911Email: [email protected]

Helpline reephone:0808 100 2040

Disclaimer

While steps have been taken to ensure its accuracy, WRAP cannot accept responsibility orbe held liable to any person or any loss or damage arising out o or in connection with thisinormation being accurate, incomplete o misleading. For more detail, please reer to our

Terms & Conditions on our website - www.wrap.org.uk

WRAP works in partnership to encourageand enable businesses and consumers tobe more ecient in their use o materialsand recycle more things more oten. This

helps to minimise landll, reduce carbonemissions and improve our environment.

materials recycling facilities _specifications, operations & costs _key studies wrap2003

Documents