mechanical biological treatment of municipal solid …...municipal solid waste (msw) is waste...

Mechanical Biological Treatment ofMunicipal Solid Waste

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Contents

Preamble 1

1. Introduction 2

2. How it works 4

3. Markets and outlets for the outputs 9

4. Track record 17

5. Contractual and financing issues 20

6. Planning and permitting issues 22

7. Social and perception issues 28

8. Cost 30

9. Contribution to national targets 31

10. Further reading and sources of information 34

11. Glossary 35

Prepared by Enviros Consulting Limited on behalf of Defra as part of the New Technologies Supporter Programme.

We acknowledge support from the Department for Environment, Food & Rural Affairs (Defra), the Department ofCommunities & Local Government (DCLG), the Environment Agency (EA) and BeEnvironmental Ltd.

This Document has been produced by Enviros Consulting Limited (Technical Advisors) on behalf of Defra to provideassistance to Local Authorities and the waste management market generally through awareness raising of the keymunicipal waste management options for thediversion of BMW from landfill. The Document has been developed ingood faith by the Advisors on behalf of Defra, and neither Defra not its Advisers shall incur any liability for any actionor omission arising out of any reliance being placed on the Document by any Local Authority or organisation or otherperson. Any Local Authority or organisation or other person in receipt of this Document should take their own legal,financial and other relevant professional advice when considering what action (if any) to take in respect of any wastestrategy, initiative, proposal, or other involvement with any waste management option or technology, or beforeplacing any reliance on anything contained therein.

Any interpretation of policy in this document is that of Enviros and not of Defra or DCLG.

Crown copyright, 2007

Cover image (MBT facility in Lübbecke, Germany) courtesy of Gesellschaft zur Verwertung organischer Abfälle (GVoA)mbH Co. KG.

Preamble

This Waste Management Technology Brief,updated in 2007, is one of a series ofdocuments prepared under the NewTechnologies work stream of the Defra WasteImplementation Programme. The Briefsaddress technologies that may have anincreasing role in diverting Municipal SolidWaste (MSW) from landfill. They provide analternative technical option as part of anintegrated waste strategy, having thepotential to recover materials & energy andreduce the quantity of MSW requiring finaldisposal to landfill. Other titles in this seriesinclude: An Introductory Guide to WasteManagement Options, Advanced BiologicalTreatment, Mechanical Heat Treatment,Advanced Thermal Treatment, Incineration,Renewable Energy and Waste Technologies,and Managing Outputs from WasteTechnologies.

The prime audience for these Briefs are localauthorities, in particular waste managementofficers, members and other key decisionmakers for MSW management in England. Itshould be noted that these documents areintended as guides to each generictechnology area. Further information can befound at the Waste Technology Data Centre,funded by the Defra New TechnologiesProgramme and delivered by theEnvironment Agency (www.environment-agency.gov.uk/wtd). These Briefs dealprimarily with the treatment and processingof residual MSW. Information on thecollection and markets for source segregatedmaterials is available from Defra and fromROTATE (Recycling and Organics TechnicalAdvisory Team) at the Waste & ResourcesAction Programme (WRAP).

These waste technologies can assist in thedelivery of the Government’s key objectives,as outlined in The Waste Strategy for England2007, for meeting and exceeding the LandfillDirective diversion targets, and increasingrecycling of resources and recovery of energy

The Defra New Technologies DemonstratorProgramme has provided nine projects aimedat proving the economic, social andenvironmental viability (or not) of a selectionof waste management technologies. Forinformation on the demonstrator projects seethe Defra website or [email protected].

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1. Introduction

Municipal Solid Waste (MSW) is wastecollected by or on behalf of a local authority.It comprises mostly household waste and itmay include some commercial and industrialwastes. Historically, the quantity of MSW hasrisen year on year1, presenting a growingproblem for local authorities particularly aslegislation that limits (by implication2) theamount of mixed MSW that can be sent tolandfill, becomes more stringent over time.

One of the guiding principles for Europeanand UK waste management has been theconcept of a hierarchy of waste managementoptions, where the most desirable option isnot to produce the waste in the first place(waste prevention) and the least desirableoption is to dispose of the waste to landfillwith no recovery of either materials and/orenergy. Between these two extremes thereare a wide variety of waste treatment optionsthat may be used as part of a wastemanagement strategy to recover materials(for example furniture reuse, glass recyclingor organic waste composting) or generate

energy from the wastes (for example throughincineration, or digesting biodegradablewastes to produce usable gases).

At present more than 62% of all MSWgenerated in England is disposed of inlandfills3. However, European and UKlegislation has been put in place to limit theamount of biodegradable municipal waste(BMW) sent for disposal in landfills4. TheLandfill Directive also requires waste to bepre-treated prior to disposal. The diversion ofthis material is one of the most significantchallenges facing the management of MSW inthe UK.

There are a wide variety of alternative wastemanagement options and strategies availablefor dealing with MSW to limit the residualamount left for disposal to landfill. The aimof this guide is to provide impartialinformation about the range of technologiesreferred to as Mechanical BiologicalTreatment (MBT). MBT technologies are pre-treatment technologies which contribute tothe diversion of MSW from landfill when

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1 This is now showing signs of slowing down and in some areas waste arisings are falling, and indeed in 2005/6 there was a 3% fall nationally.However, this may be partly explained by other factors occurring in that particular financial year.

2 Targets pertain to the biodegradable fraction in MSW3 Results from WasteDataFlow http://www.defra.gov.uk/environment/statistics/wastats/bulletin.htm4 The Landfill Directive, Waste and Emissions Trading Act 2003 and Landfill Allowances Trading Scheme Regulations

1. Introduction

operated as part of a wider integratedapproach involving additional treatmentstages. They are part of a range ofalternatives currently being assessed andinvestigated through the New Technologieswork stream of Defra. Further details aboutthe new technologies featured in this reportare available from Defra’s Waste TechnologyData Centre:

http://www.environment-agency.gov.uk/wtd

The technologies described in this Brief havea varying track record in the UK. Earlyexamples of similar processes in the UKincluded ‘Refuse Derived Fuel’ (RDF)processing plant and residual waste MaterialsRecovery Facilities (‘Dirty MRFs’). This earlygeneration of mixed waste processing

facilities often encountered technical andmarketing difficulties during operation andmost have closed or been reconfigured. Thenew MBT technologies are now second orthird generation plant including many wellproven examples. On the continent many ofthese processes are established, viable andbankable. The aim of this document is to raiseawareness and help bring the UK up to thatstandard.

This guide is designed to be read inconjunction with the other WasteManagement Technology Briefs in this seriesand with the case studies provided on theWaste Technology Data Centre. Otherrelevant sources of information are identifiedthroughout the document.

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2. How it works

MBT is a generic term for an integration ofseveral processes commonly found in otherwaste management technologies such asMaterials Recovery Facilities (MRFs), sortingand composting or anaerobic digestion plant.MBT plant can incorporate a number ofdifferent processes in a variety ofcombinations. Additionally, MBT plant can bebuilt for a range of purposes. This sectionprovides an overview of the range oftechniques employed by MBT processes.

2.1 The Aim of MBT Processes

MBT is a residual waste treatment processthat involves both mechanical and biologicaltreatment processes. The first MBT plantswere developed with the aim of reducing theenvironmental impact of landfilling residualwaste. MBT therefore compliments, but doesnot replace, other waste managementtechnologies such as recycling andcomposting as part of an integrated wastemanagement system.

A key advantage of MBT is that it can beconfigured to achieve several different aims.In line with the EU Landfill Directive andnational recycling targets, some typical aimsof MBT plants include the:

• Pre-treatment of waste going to landfill;• Diversion of non-biodegradable and

biodegradable MSW going to landfillthrough the mechanical sorting of MSWinto materials for recycling and/or energyrecovery as refuse derived fuel (RDF);

• Diversion of biodegradable MSW going tolandfill by:- Reducing the dry mass of BMW prior to

landfill;- Reducing the biodegradability of BMW

prior to landfill;

• Stabilisation into a compost-like output(CLO)5 for use on land;

• Conversion into a combustible biogas forenergy recovery; and/or

• Drying materials to produce a high calorificorganic rich fraction for use as RDF.

MBT plants may be configured in a variety ofways to achieve the required recycling,recovery and biodegradable municipal waste(BMW) diversion performance. Figure 1illustrates configurations for MBT andhighlights the components within each. ABTis an acronym for an Advanced BiologicalTreatment process, which are covered in aseparate Technology Brief in this series andfurther information is available on the WasteTechnology Data Centre concerning differentconfigurations of plant.

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5 Compost-like Output (CLO) is also sometimes referred to as ‘stabilised biowaste’ or a soil conditioner; it is not the same as a source-segregated waste derived ‘compost’ or ‘soil improver’ that will contain much less contamination and has a wider range of end uses

2. How it works

2.2 Waste Preparation

Residual waste requires preparation beforebiological treatment or sorting of materialscan be achieved. Initial waste preparationmay take the form of simple removal ofcontrary objects, such as mattresses, carpetsor other bulky wastes, which could causeproblems with processing equipment down-stream.

Further mechanical waste preparationtechniques may be used which aim to prepare

the materials for subsequent separationstages. The objective of these techniquesmay be to split open refuse bags, therebyliberating the materials inside; or to shredand homogenise the waste into smallerparticle sizes suitable for a variety ofseparation processes, or subsequent biologicaltreatment depending on the MBT processemployed.

A summary of the different techniques usedfor waste preparation is provided in Table 1.

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Figure 1: An illustration of the potential Mechanical Biological Treatment options

Biogas

Landfill Landfill

Sorting before ABT

ABT before sorting e.g. biodrying

Pre-treatment before landfill

Waste Preparation

Sorting ABT

Compost likeoutputs

Refusederived fuel

Recyclablematerials

Market failure/rejects

2. How it works

2.3 Waste Separation

A common aspect of many MBT plant usedfor MSW management in the sorting ofmixed waste into different fractions usingmechanical means. As shown in Figure 1, thesorting of material may be achieved before orafter biological treatment. No sorting isrequired if the objective of the MBT process isto pre-treat all the residual MSW to producea stabilised output for disposal to landfill.

Sorting the waste allows an MBT process toseparate different materials which aresuitable for different end uses. Potential enduses include material recycling, biological

treatment, energy recovery through theproduction of RDF, and landfill. A variety ofdifferent techniques can be employed, andmost MBT facilities use a series of severaldifferent techniques in combination toachieve specific end use requirements fordifferent materials.

Separation technologies exploit varyingproperties of the different materials in thewaste. These properties include the size andshape of different objects, their density,weight, magnetism, and electricalconductivity. A summary of the differentoptions for waste separation is shown inTable 2.

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Ref Technique Principle Key Concerns

A Hammer Mill Material significantly reduced in size byswinging steel hammers

Wear on Hammers, pulverising and‘loss’ of glass / aggregates, exclusion ofpressurised containers

B Shredder Rotating knives or hooks rotate at a slow speedwith high torque. The shearing action tears orcuts most materials

Large, strong objects can physicallydamage, exclusion of pressurisedcontainers

C RotatingDrum

Material is lifted up the sides of a rotating drumand then dropped back into the centre. Usesgravity to tumble, mix, and homogenize thewastes. Dense, abrasive items such as glass ormetal will help break down the softer materials,resulting in considerable size reduction of paperand other biodegradable materials

Gentle action – high moisture offeedstock can be a problem

D Ball Mill Rotating drum using heavy balls to break up orpulverise the waste

Wear on balls, pulverising and ‘loss’ ofglass / aggregates

E Wet RotatingDrum withKnives

Waste is wetted, forming heavy lumps whichbreak against the knives when tumbled in thedrum

Relatively low size reduction. Potentialfor damage from large contraries

F Bag Splitter A more gentle shredder used to split plastic bagswhilst leaving the majority of the waste intact

Not size reduction, may be damaged bylarge strong objects

Table 1: Waste Preparation Techniques

2. How it works

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Figure 2: Waste separation using a trommel screen

Table 2: Waste Separation Techniques

Separation Technique Separation Property Materials targeted Key Concerns

1 Trommels and Screens Size Oversize – paper, plastic

Small – organics, glass, fines

Air containment andcleaning

2 Manual Separation Visual examination Plastics, contaminants,oversize

Ethics of role, Health &Safety issues

3 Magnetic Separation Magnetic Properties Ferrous metals Proven technique

4 Eddy CurrentSeparation

Electrical Conductivity Non ferrous metals Proven technique

5 Wet SeparationTechnology

Differential Densities Floats - Plastics, organics

Sinks - stones, glass

Produces wet wastestreams

6 Air Classification Weight Light – plastics, paper

Heavy – stones, glass

Air cleaning

7 Ballistic Separation Density and Elasticity Light – plastics, paper

Heavy – stones, glass

Rates of throughput

8 Optical Separation Diffraction Specific plastic polymers Rates of throughput

2. How it works

2.4 Biological Treatment

The biological element of an MBT process cantake place prior to or after mechanical sortingof the waste, as illustrated in Figure 1. Insome processes all the residual MSW isbiologically treated to produce a stabilisedoutput for disposal to landfill and no sortingis required. The biological processes used areeither:

• Aerobic Bio-drying• Aerobic In-vessel composting• Anaerobic digestion

Each approach has its own particularapplication and examples of methodologiesare described in the case studies in the trackrecord section and in more detail on theWaste Technology Data Centre.

There are a variety of different biologicaltreatment techniques which are used in MBTplant. These are described in greater detail inthe Advanced Biological Treatment Brief, inthis series. Table 3 below outlines the keycategories of biological treatment.

Table 3: Biological Treatment options

2.5 Summary

This section illustrates that MBT systems canbe described as two simple concepts: either toseparate the waste and then treat; or to treatthe waste and then separate. In somesystems only biological treatment is requiredto treat all the residual MSW before disposalto landfill. Whilst a variety of treatment andmechanical separation options are offered,these need to be optimised in terms of theoutputs in order to find outlets for thevarious materials / fuels derived from theprocess (see Markets for the Outputs section).

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Options Biological Treatment

I Aerobic - Bio-drying / Biostabilisation:partial composting of the (usually) wholewaste

II Aerobic - In-Vessel Composting: may beused to either biostabilise the waste orprocess a segregated organic rich fraction

III Anaerobic Digestion: used to process ansegregated organic rich fraction

3. Markets and outlets for the outputs

In the UK, at present, the market or outlet formany of the outputs from MBT is still underdevelopment. Plants being specified todaywill need to provide materials into as yetundeveloped markets. It is prudent to installor at least maintain the option of installingfor flexibility in the degree and types ofseparation of materials that any proposedplant can achieve.

The following section summarises some keyissues with regard to the outlets for outputsfrom MBT systems for MSW.

3.1 Materials Recycling

Recyclables derived from the various MBTprocesses are typically of a lower quality thanthose derived from a separate householdrecyclate collection system and therefore havea lower potential for high value markets. Thetypes of materials recovered from MBTprocesses almost always include metals(ferrous and non-ferrous) and for manysystems this is the only recyclate extracted.However these plant can help enhance overallrecycling levels and enable recovery of certainconstituent items that may not otherwise becollected in household systems (e.g. batteries,steel coat hangers, etc.).

Other materials which may be extracted fromMBT processes include glass, textiles, paper /card, and plastics. The most common of theseis glass, which may be segregated with otherinert materials such as stones and ceramics.These materials are typically segregated andarise as the “dense” fraction from airclassifiers or ballistic separation (see Table 2on mechanical waste preparationtechnologies). This dense fraction could findapplication for use as a low grade aggregate;however this would be subject to achieving asuitable quality material. This mixed materialfrom some processes has found application asAlternative Daily Cover (ADC) at landfill sites,though this would not count towardsrecycling performance or diversion fromlandfill.

Segregating glass for recycling from residualwaste or a mixed waste arising from an MBTplant would require material-specific sortingtechniques if recycling into high-valueproducts is to be achieved. Examples of thisapproach can be found both in MBT plant aswell as more traditional “dirty MRF”processes treating mixed residual waste inother countries. In these examples manualsorting of glass has been applied to segregatethe material. However, labour costs in the UKare considered to be high, and are likely topreclude this approach as being uneconomic.There are also significant issues with respectto worker Health and Safety, and thehandling of broken glass objects from mixedwaste streams.

Textiles, paper and plastics, if extracted, areunlikely to receive an income as a recyclateand in some instances may not yield a positivevalue. Most of these plant can experienceproblems with the heavier textiles such ascarpets. Clearly none are likely to separatetextiles into different types of fibre.

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Although unlikely, paper can potentially beseparated for recycling but often it iscombined with textiles and plastics; recyclingmarkets or outlets for the material are verylimited. Manual sorting or moresophisticated mechanical sorting can beundertaken on this waste stream. The qualityof the paper will be lower than if sourcesegregated and the markets available will befewer and of lower value. With theimproving performance of kerbside recyclingschemes there has been an increase in thequantity of paper separately collected forrecycling. This paper will be able to secure amarket, either in the UK or overseas, moreeasily than paper separated in an MBT facility.Consequently, few MBT processes attempt tosegregate paper for recycling, preferringinstead to utilise it as a high calorific valueRefuse Derived Fuel (RDF), which is easilyachieved using conventional mechanicalsorting techniques.

Any plastics separated from these processeswill almost always be mixed plastics. The useof high-tech optical sorting technology, suchas Near Infra-Red (NIR), offers the potential torecover high value material-specific wastestreams, such as segregated plastic bypolymer type. Application of such techniquesis currently rare in MBT processes, and itseffectiveness is yet to be fully proven inresidual waste applications. The capital costsassociated with installing such technologiesare high, and cost/benefits of adopting themwould be significantly influenced by theeffectiveness of any recycling achievedupstream through kerbside collection systemsserving to limit the quantity of recyclablematerials present in residual waste.

For more information on the contribution ofMBT to Best Value Performance Indicatorsand recycling see section 9, and for the latestdevelopments see the local authority

performance pages on the Defra websitehttp://www.defra.gov.uk/environment/waste/localauth/perform-manage/index.htm andhttp://www.wastedataflow.org/Documents/BVPI%20FAQs.pdf

3.2 Use of compost-like outputs (CLO)

MBT processing of mechanically separatedorganics can produce partially/fully stabilisedand sanitised CLO or partially stabiliseddigestate material. Digestate material isproduced from an MBT process that usesanaerobic digestion as the biological process.CLO is usually the term used for an outputusing an aerobic process such as bio-drying orin-vessel composting. The potentialapplications of these outputs are dependentupon their quality and legislative and marketconditions. CLO and digestate has thepotential to be used as a source of organicmatter to improve certain low quality soils,e.g. in the restoration of brown field sites, orfor landfill cap restoration.

A summary of the estimated size of thepotential market outlets for CLO is given intable 4.

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It is generally assumed that CLO derived frommixed waste will be of lower quality andvalue compared to compost derived fromsource-segregated materials, largely due tohigher contamination levels. Trials on mixedwaste derived materials have reported8 largeamounts of physical contaminants (e.g. glass)

and levels of potentially toxic elements abovelimits for the British Standards Institute (BSI)Publicly Available Specification (PAS) 100: forcomposted materials, in particular for zinc,lead, cadmium and mercury. Table 5 showsthe limits for heavy metals and other criteriafor PAS 100 compost.

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Material Application Potential market in Tonnes per year Source

Soil Conditioner / Organicbased output from MBT

Land Restoration /Remediation

1,300,000 – 11,900,000

NB: a variety of scenarios considered to constitute this range

Sita Trust20056


Land Restoration /Remediation

>6,000,000 WRAP20027


Landfill Cap /Restoration

1,200,000 – 4,600,000

NB: a variety of scenarios considered toconstitute this range

Sita Trust 2005


Landfill Cap /Restoration

>5,000,000 WRAP2002

Table 4: Market outlets for CLO

6 MBT: A Guide for Decision Makers- Processes, Policies and Markets, Juniper Consultancy 2003 (produced for SITA Trust7 Research Analysis for the Market Potential for Lower Grade Composted Materials in the UK, WRc, 2002 (for WRAP)8 Development of a dynamic housed windrow composting system: performance testing and review of potential use of end products, ORA

(March 2005) for Canford Environmental

Table 5: BSI PAS 100 criteria*

* BSI PAS 100 is only valid for composts derived from source segregated waste, by definition

Parameter BSI PAS 100 limit

Cadmium, ppm 1.5

Chromium, ppm 100

Copper, ppm 200

Mercury, ppm 1

Nickel, ppm 50

Lead, ppm 200

Zinc, ppm 400

Impurities >2mm 0.5%; of which 0.25% maximum can be plastic

Gravel & stones>4mm <8% in grades other than coarse mulch;

>4mm in coarse mulch grade <16%

Pathogens E.coli 1000 cfu/g; No Salmonella in 25g

Microbial respiration rate 16 mg CO2/g organic matter/day


The quality of CLO produced will vary withdifferent MBT technologies, the quality ofraw waste inputs, and the method andintensity of waste preparation and separationprior to biological treatment, as well as themethods used to screen of the outputs.

Due to its low quality, opportunities to applyCLO or digestate produced from mixed MSWto land will be limited. As a waste, thesematerials require a waste managementlicence (WML) exemption in order to be usedon land. Currently, they can only be used onnon-agricultural land and must be shown tobe ecologically beneficial. A risk-basedassessment is needed in relation to theircontamination content, and the nature of theland to which they are to be applied. This issimilar approach to regulations covering theuse of sewage sludge in agriculture. CLO ordigestate that is used on land must also meetthe requirements of the Animal By-ProductsRegulations (ABPR).

If an outlet cannot be found for the CLO thenit may have to be disposed to landfill. Thiswill incur a disposal cost and anybiodegradability remaining will contribute tolocal authority BMW landfill allowancesunder LATS (the Landfill Allowance TradingScheme). For more information on LATS seehttp://www.defra.gov.uk/environment/waste/localauth/lats/index.htm.

Waste Management Licensing Regulations

Changes to the Waste Management LicensingRegulations came into force on 1st July 20059.A waste management licence (WML)exemption, under Paragraph 7A of theregulations, is required by landowners/managers before any compost or

digestate (fibre or effluent) derived fromsource-segregated waste materials can beapplied to agricultural land10. CLO, derivedfrom mixed waste, is not allowed to beapplied to agricultural land. These outputsmay be applied to brownfield and restorationland under a WML exemption, underParagraph 9A, provided that ecologicalbenefit is demonstrated.

The Government and the National Assemblyfor Wales consulted in May 2006 on therequirement for compost or digestate derivedfrom source-segregated materials for it to bepermitted to be spread to agricultural land,under a Paragraph 7A WML Exemption. Inthe light of consultation, the Government hasconcluded that, for now, the source-segregation requirement should remain.However, the Government views this as aninterim measure, and will carry out work tofind a longer term, more sustainable solutionthat will encourage the development of[mixed MSW ABT] technologies that willproduce high standard outputs which couldbe safely spread to land.

Animal By-Products Regulations (ABPR)

MBT plants that intend to use the stabilisedorganic material on land (including landfillcover) will be considered to be a compostingor biogas plant, and will fall within the scopeof the ABPR. These sites must therefore meetall treatment and hygiene standards requiredby source-segregated waste composting/biogas plants.

Mixed MSW will contain household kitchen(‘catering’) waste including meat, and as suchwill, at least, fall under UK national ABPR11

standards for catering waste containing meat.

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9 The Waste Management Licensing (England and Wales) (Amendment and Related Provisions) (No. 3) Regulations 2005 (S.I. No. 1728)10Unless the Quality Protocol for Compost applies for source segregated biowaste - The Quality Protocol for the production and use of quality

compost from source-segregated biowaste, developed by the Business Resource Efficiency and Waste (BREW) programme, WRAP and theEnvironment Agency, published March 2007

11Animal By-products Regulations 2003 (SI 2003/1482); Wales (SI 2003/2756 W.267); Scotland (SSI 2003/411)


In some cases it may also contain certaincommercial/industrial waste containing rawmeat or fish; classified as ‘Category 3’ animalby-products. Category 3 animal by-productsmust be treated in accordance with the EUregulation12 standards.

3.3 Production of biogas

An MBT plant that uses anaerobic digestion(AD) as its biological process will producebiogas. During AD, the biodegradablematerial is converted into methane (CH4) andcarbon dioxide (together known as biogas),and water, through microbial fermentation inthe absence of oxygen leaving a partiallystabilised wet organic mixture known as adigestate.

The biogas can be used in a number of ways.It can be used as a natural gas substitute(distributed into the natural gas supply) orconverted into fuel for use in vehicles. Morecommonly it is used to fuel boilers to produceheat (hot water and steam), or to fuelgenerators in combined heat and power(CHP) applications to generate electricity, aswell as heat.

Biogas electricity production per tonne ofwaste can range from 75 to 225 kWh, varyingaccording to the feedstock composition,biogas production rates and electricalgeneration equipment. Biogas is a source ofrenewable energy, with electricity generatedfrom it being supporter by the RenewablesObligation.

In most simple energy productionapplications, only a little biogas pre-treatment is required. Biogas used in a boilerrequires minimal treatment and compression,

as boilers are much less sensitive to hydrogensulfide and moisture levels, and can operateat a much lower input gas pressure.

Where biogas is used for onsite electricitygeneration, a generator similar to that usedin landfill gas applications can be used, asthese generators are designed to combustmoist gas containing some hydrogen sulfide.Gas compression equipment may be requiredto boost the gas pressure to the levelrequired by the generator.

Some electricity is used by the AD plant, butany excess electricity produced can be soldand exported via the local electricitydistribution network. Excess heat can also beused locally in a district heating scheme, ifthere is an available user.

For high specification applications (e.g.vehicle fuel, natural gas substitute), or whenusing more sophisticated electricitygeneration equipment (e.g. turbines), biogaswill require more pre-treatment to upgradeits quality. This includes the removal ofhydrogen sulphide (a corrosive gas); moistureremoval; pressurization to boost gas pressure;and removing carbon dioxide to increase thecalorific value of the biogas. However, thecost of the equipment required to upgradebiogas can be prohibitive.

3.4 Materials Recovered for Energy

Where the MSW is sorted / treated to producea high calorific value waste stream comprisingsignificant proportions of the availablecombustible materials such as mixed paper,plastics and card, this stream may be knownas Refuse Derived Fuel (RDF - see Box 1)

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12 Regulation EC 1774/2002 laying down health rules concerning animal by-products not intended for human consumption


Potential outlets for RDF

Defra has identified 6 potential outlets forRDF. The viability of some of these isdependent on legislative changes beingmade, which may or may not happen. The 6potential outlets are:

1. Industrial intensive users for power, heat orboth (Combined Heat and Power - CHP)

2. Cement kilns3. Purpose built incinerators with power

output or power and heat (CHP)4. Co-firing with coal at power stations

5. Co-firing with fuels like poultry litter andbiomass which are eligible for RenewableObligation Certificates (ROCs – see section3.3.2) in conventional technologies

6. Advanced thermal technologies, such aspyrolysis and gasification which are ROCeligible technology

RDF from a UK MBT facility is already utilisedat a cement works as an energy source,replacing other fuels. Industrial intensiveenergy users are not yet using RDF but someinterest from industry is being shown in themarket place.

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The current prevalent term used for a fuelproduced from combustible waste is RefuseDerived Fuel (RDF). The types of technologiesused to prepare or segregate a fuel fractionfrom MSW include the MBT processes describedwithin this Brief.

A CEN Technical Committee (TC 343) is currentlyprogressing standardisation work on fuelsprepared from wastes, classifying a SolidRecovered Fuel (SRF). Preliminary standards havebeen published in June 2006, and are followingan evaluation process, during which thefunctioning of the specifications will be verified.The technical specifications classify the SRF bythermal value, chlorine content and mercurycontent. For example, the thermal value classwill be based on the number of megajoules onekilogram of recovered fuel contains. In addition,there are many characteristics for which nospecific values have been determined. Instead,they can be agreed upon between the producerand the purchaser of SRF.

Along with the standardisation process, avalidation project called QUOVADIS(http://quovadis.cesi.it/) on solid recovered fuelsis currently being implemented.

It is anticipated that once standards aredeveloped and become accepted by users, thenSRF will become the terminology used by thewaste management industry. Other terminologyhas also been introduced to the industry asvarious fuel compositions may be prepared fromwaste by different processes. Examples include‘Biodegradable Fuel Product’ (BFP) and ‘RefinedRenewable Biomass Fuel’ (RRBF).

European standards for SRF are important forthe facilitation of trans-boundary shipments andaccess to permits for the use of recovered fuels.There may also be cost savings for co-incineration plants as a result of reducedmeasurements (e.g. for heavy metals) ofincoming fuels. Standards will aid therationalisation of design criteria for combustionunits, and consequently cost savings forequipment manufacturers. Importantly standardswill guarantee the quality of fuel for energyproducers.

Within this Brief, Refuse Derived Fuel will beused as a term to cover the various fuel productsprocessed from MSW.

Box 1: Fuel from mixed waste processing operations


There is currently only one dedicatedconventional combustion plant (incinerator)in the UK that uses RDF as a fuel to generateelectricity. Another facility which acceptsprepared fuel, (generated from raw MSWdelivered at the front end of the plant) whichcould be termed crude RDF is also combustedin a recently commissioned Fluidised-Bedincinerator in Kent, illustrated in Table 6.

Table 6: Combustion technology plantgenerating electricity from RDF in England

RDF may also be utilised within someappropriate Advanced Thermal Treatment(ATT) processes. A suitably scaled, dedicatedATT plant could represent a part of anintegrated strategy in combination with MBT.A separate Waste Management TechnologyBrief, in this series, is available on the subjectof ATT processes.

The energy use incurred in the separation ofwaste typically involves around 15 – 20% ofthe energy value of the waste. If the RDF is tobe used as an energy source then a highefficiency process (e.g. Advanced ThermalTreatment or Incineration with CombinedHeat and Power) needs to be used, or theRDF needs to be used as a fossil-fuelreplacement fuel to establish anyenvironmental benefit over directlycombusting the residual waste in anincinerator. Not all ATT processes will offerthe efficiencies appropriate.

The advantage of co-combusting RDF atpower stations or other large thermalprocesses is that the infrastructure mayalready be in place; a disadvantage is that theoutlet for the fuel is subject to obtaining acontract of sufficient duration and tonnage,with a commercial partner. An estimate ofthe potential market for RDF in the UK isprovided in the table 7 below.

Table 7: Estimated size of the RDF market

The co-combustion of RDF is an emergingmarket. It is currently anticipated that cementkilns along with large industrial energy usersand the power generation sector will providethe majority of potential capacity for usingRDF. There is however, competition fromother wastes to be processed within thecement production process including tyres,some hazardous wastes, secondary liquidfuels etc. Consequently it is expected thatthere may be competition (and competitivegate fees) for acceptance of RDF at cement

15

RDF Combustionplant

Operator K tonnes/ year

Slough,Berkshire

Slough Heat &Power

100

Allington, Kent

KentEnviropower

500

13RDF Opportunities: Coal and Cement Industries, Fichtner Consulting, RRF 200414 Submission of Evidence to House of Commons Select Committee, January 2003

Output OutletPredicted

Market size(t/a)

Source

RDF UK CementKilns

350,000 ResourceRecoveryForum,200413

Packaging &Packagingwaste (incl.municipalderived RDF)

UK CementKilns

500,000 BritishCementAssociation,200314

RDF PaperIndustry

300,000 –600,000 NB: Requiredconstructionof dedicatedRDF plant atpaper mills

ResourceRecoveryForum,2004


kilns. A local authority currently would haveto pay for the RDF to be used in a cementkiln. Emphasis should be put on developingsustainable markets for materials

As an emerging market there are alsopotential risks in terms of the operations oflarge thermal facilities accepting RDF frommixed waste processing as a fuel source.However, waste contractors are developingrelationships with the cement industry andothers to try and meet their specificationsand provide a useful industrial fuel and wasterecovery operation.

Renewable Energy

RDF is classified as a waste and therefore anyfacility using the fuel will be subject to therequirements of the Waste IncinerationDirective (WID). As with the cement industry,power stations would need to be WIDcompliant. This would represent a significantcapital investment for the industry. HoweverWID only requires an operator to upgradethose facilities at a power station in which

waste is handled to WID standards15. If anoperator has more than one boiler then onlyone would need to be upgraded. This mightmake RDF a more attractive option for thepower generation industry.

Electricity generated from the biodegradablefraction of waste in certain technologies iseligible for support under the RenewablesObligation (RO). Electricity recovered fromthe biomass component of RDF qualifies forsupport if it is generated in ‘advancedconversion technologies’, including pyrolysisor gasification plant (see the AdvancedThermal Treatment Brief), or in aconventional combustion facility with GoodQuality Combined Heat and Power (CHP)

Up-to-date information regarding RDF andROCs can be obtained from the DTI websitehttp://www.dti.gov.uk/energy/renewables/.Also see the Defra New TechnologiesDemonstrator Programme for demos usingRDF.

16

15Written answers to Alan Whitehead MP from Ben Bradshaw, Minister of State for Defra, 07/03/2007

4. Track record

The concept of MBT originated in Germanywhere it is an established waste treatmentmethod. Regulatory restrictions on landfillspace, the search for alternatives toincineration and increased costs of landfilldisposal have been the major drivers for thedevelopment of these technologies. Thelargest European markets for established MBTplant include Germany, Austria, Italy,Switzerland and the Netherlands, with otherssuch as the UK growing fast. Furthermore,other countries outside Europe are also usingthis technology.

Since the early 1990s, MBT processes havechanged significantly, so today, numerousconfigurations of plant have developed, andthese are provided by a variety of companies.

There are over 70 MBT facilities in operationin Europe, with over 40 MBT facilitiesoperating in Germany. However, not all ofthese facilities are commercial and some ofthose included in Table 8 include pilot anddemonstration plants.

Table 8: Examples of MBT plant operationalin Europe

17

Technology Provider CountryNumberof Plants

Hese Umwelt (Leicester) UK 1

EcoDeco (ELWA) UK 1

Civic Environmental Systems(Durham)

UK 1

New Earth Solutions (Dorset) UK 1

CRS (Argyll and Bute,Northumberland)

UK 2

Hot Rot (Western Isles) UK 1

Sutco Germany 5

Electrowatt-Ekono Germany 1

Herhof Germany 3

Dranco Germany 2

ISKA Germany 1

Horstmann Germany 4

Wehrle Werk Germany 1

BTA Germany 1

BTA Italy 1

Dranco Italy 1

Ionics Itabila Italy 1

Snamprogetti Italy 1

Valorga Italy 1

EcoDeco Italy 4

Herhof Italy 1

Valorga Spain 2

Linde Spain 1

Dranco Spain 1

BTA/Roediger Poland 1

Citec Finland 1

Citec/Vagron Holland 1

Valorga Belgium 1

Valorga France 2

Valorga Netherlands 1

Dranco Switzerland 1

Dranco Austria 1

VKW Austria 1

VKW Italy 1

VKW Turkey 1

4. Track record

4.1 Case Studies

The following case studies illustrate examplesof MBT system using the different mechanicalpreparation, separation and biologicaltreatment techniques, described in Section 2.

Shanks East London Sistema Ecodeco MBTfacility on Frog Island

This facility is designed to take up to 180,000tonnes per year of mixed residual waste fromthe East London Waste Authority. It is a fullyenclosed bio-drying system. Waste is shreddedbefore being placed into a bio-drying areawhere the material is treated using a suctionforced-aeration system in the floor. Thematerial is biologically treated for two weeks.The dry material is then put through amechanical separation process to removemetals and a glass / aggregate fraction. Theremaining dried waste (consisting mainly ofdried organics, card, paper, plastics and othermiscellaneous materials) is highly calorific andused as RDF. The RDF is currently used by acement kiln, however, it will be utilised by anAdvanced Thermal Treatment (ATT) processoperated by Novera Energy Ltd at the FordDagenham plant, which will be part fundedby the Defra New Technologies Demonstratorprogramme.

Bournemouth Council’s New Earth MBTfacility

The £4.4 million New Earth MBT facility basedat Poole in Dorset is designed to take 50,000tonnes per year of mixed MSW. The waste isshredded and an organic-rich fraction isscreened out. The organic fraction is thencomposted in elongated piles (windrows)placed on forced-aeration ducts inside one oftwo composting buildings. The material isturned using specialised machinery 3 timesduring a two-week process. The material is

then composted in a second building withsuction forced aeration for a further twoweeks. The facility produces around 9,000tonnes of compost-like output per year.

Earth Tech Western Isles MBT facility

This is a £10 million project to build 2treatment facilities. The main facility inStornoway on the Isle of Lewis treats 21,000tonnes per year of source-separated organicsand residual waste. Anaerobic digestion(using Linde technology) is used to treat thesource separated waste and in-vesselcomposting (by HotRot) is used to treat theresidual waste. Mixed residual MSW isshredded and screened to produce a fineorganic fraction which is composted toproduce a CLO for landfill restoration.

Biffa/Leicester MBT facility and AD plant

This MBT facility (estimated to cost £20million) has a capacity of up to 150,000tonnes per year of mixed residual waste. Thefacility is spread over two sites: Bursom, hometo a large ball mill used to crush the wastebefore it is screened and classified intovarious usable fractions; and Wanlip, wherean AD facility is used to process the fine(<5mm) organic-rich fraction from the milledwaste. The AD process is designed to handleup to around 50,000 tonnes per year. The ADplant uses a two-stage process: first, the finesare made into wet slurry that is then pumpedwith air during a 24 hour aerobic hydrolysisprocess; and second, this pre-treated(biologically heated and acidified) slurry isthen sent to an 18 day thermophilic wet ADprocess. The plant is expected to produceenough biogas to provide 1.5 MW ofelectricity. The digestate undergoes furthertreatment to produce a CLO.

18

4. Track record

4.2 Summary

The case studies represent a selection of MBTprojects currently operational in the UK.Numerous MBT projects can be found abroadand especially across Europe, where MBT hasbeen well established for many years. MBTprocess configurations can vary significantlyand can be designed to suit local marketconditions and the regulatory frameworkspecific to the country in which it operates.More information on different MBT systemscan be found on the Environment Agency’swebsite in the Waste Technology Data Centre– www.environment-agency.gov.uk/wtd

MBT as illustrated by the case studies,represent significant facilities, which arecapital intensive (see Cost section) and areanticipated to be in operation for 15 – 25years. With the emergent nature ofmarkets/outlets for outputs from suchprocesses, it is prudent to ensure sufficientinstalled capacity for flexibility within anyplant (which may require new equipment,etc) to adapt to the needs of the market overtime.

19

5. Contractual and financing issues

5.1 Grants & Funding

Development of MBT plant will involvecapital expenditure of several million pounds.There are a number of potential fundingsources for Local Authorities planning todevelop such facilities, including:

Capital Grants: general grants may beavailable from national economic initiativesand EU structural funds;

Prudential Borrowing: the LocalGovernment Act 2003 provides for a'prudential' system of capital finance controls;

PFI Credits and Private Sector Financing:under the Private Finance Initiative a wasteauthority can obtain grant funding fromcentral Government to support the capitalexpenditure required to deliver new facilities.This grant has the effect of reducing thefinancing costs for the Private Sector, therebyreducing the charge for the treatment service;

Other Private-Sector Financing: Acontractor may be willing to enter a contractto provide a new facility and operate it. Thecontractor’s charges for this may be expressedas gate fees; and

Existing sources of local authorityfunding: for example National Non-DomesticRate payments (distributed by centralgovernment), credit (borrowing) approvals,local tax raising powers (council tax), incomefrom rents, fees, charges and asset sales(capital receipts). In practice capacity for thiswill be limited.

The Government is encouraging the use ofdifferent funding streams, otherwise knownas a ‘mixed economy’ for the financing andprocurement of new waste infrastructure toreflect the varying needs of local authorities.

5.2 Contractual Arrangements

Medium and large scale municipal wastemanagement contracts are likely to bethrough the Competitive Dialogue procedureunder the Public Contract Regulations (2006).

The available contractual arrangementbetween the private sector provider (PSP) andthe waste disposal authority (or partnership)may be one of the following:

Separate Design; Build; Operate; andFinance: The waste authority contractsseparately for the works and services needed,and provides funding by raising capital foreach of the main contracts. The contract tobuild the facility would be based on thecouncil’s design and specification and thecouncil would own the facility onceconstructed;

Design & Build; Operate; Finance: Acontract is let for the private sector to provideboth the design and construction of a facilityto specified performance requirements. Thewaste authority owns the facility that isconstructed and makes separatearrangements to raise capital. Operationwould be arranged through a separateOperation and Maintenance contract;

Design, Build and Operate; Finance: TheDesign and Build and Operation andMaintenance contracts are combined. Thewaste authority owns the facility onceconstructed and makes separatearrangements to raise capital;

Design, Build, Finance and Operate(DBFO): This contract is a Design and Buildand Operate but the contractor also providesthe financing of the project. The contractordesigns, constructs and operates the plant toagreed performance requirements. Regularperformance payments are made over a fixed

20

5. Contractual and financing issues

term to recover capital and financing costs,operating and maintenance expenses, plus areasonable return. At the end of the contract,the facility is usually transferred back to theclient in a specified condition;

DBFO with PFI: This is a Design, Build,Finance and Operate contract, but it isprocured under the Private Finance Initiative.In this case the waste authority obtainsfunding for future payment obligations fromGovernment as a supplement to finance fromits own and private sector sources.

The majority of large scale wastemanagement contracts currently beingprocured in England are Design, Build,Finance and Operate (DBFO) contracts andmany waste disposal authorities in two tierEnglish arrangements (County Councils) arecurrently seeking to partner with their WasteCollection Authorities (usually District orBorough Councils). Sometimes partnershipsare also formed with neighbouring UnitaryAuthorities to maximise the efficiency of thewaste management service and make thecontract more attractive to the Private SectorProvider.

Before initiating any procurement or fundingprocess for a new waste managementtreatment facility, the following issues shouldbe considered: performance requirements;waste inputs; project duration; project cost;available budgets; availability of sites;planning status; interface with existingcontracts; timescales; governance and decisionmaking arrangements; market appetite andrisk allocation.

Further guidance on these issues can beobtained from the following sources:

• Local Authority fundinghttp://www.defra.gov.uk/environment/waste/localauth/funding/pfi/index.htm

• The Local Government PFI project supportguidewww.local.odpm.gov.uk/pfi/grantcond.pdf

• For Works Contracts: the Institution of CivilEngineers ‘New Engineering Contract’(available at www.ice.org.uk).

• For large scale Waste Services Contractsthrough PFI and guidance on waste sectorprojects see the 4ps, local government'sproject delivery organisationhttp://www.4ps.gov.uk/PageContent.aspx?id=90&tp=Y

A number of PFI funded/contracted wastemanagement projects have and will continueto involve large scale MBT technologies someof these are shown in Table 9).

Table 9: Examples of PFI Contracts in LocalAuthority Waste Management including MBTtechnology

21

YearLocal

AuthorityLead

ContractorSolutions

2003 East London Shanks 2 MBT withBio-drying

2003 Leicester Biffa MRF + AD

Inprogress

Lancashire GlobalRenewables

4 MBT + 5TransferStations

Inprogress

Cambridgeshire Donarbon 2 MBT, EfW,AD

Inprogress

Northumberland SITA 3 CivicAmenitysites, MRF,MBT,composting

6. Planning and permitting issues

This section contains information on theplanning and regulatory issues associatedwith MBT facilities based on legislativerequirements, formal guidance, good practiceand in particular drawing on informationcontained in the Office of the Deputy PrimeMinister’s research report on waste planningpublished in August 200416.

6.1 Planning Application Requirements

All development activities are covered byPlanning laws and regulations. Minordevelopment may be allowed underPermitted Development rights but in almostall cases new development proposals forwaste facilities will require planningpermission.

Under certain circumstances new wastefacilities can be developed on sites previouslyused for General Industrial (B2) or Storageand Distribution (B8) activities. In practiceeven where existing buildings are to be usedto accommodate new waste processes,variations to existing permissions are likely tobe required to reflect changes in trafficmovements, emissions etc.

Under changes to the planning systemintroduced in 2006 all waste development isnow classed as ‘Major Development’. This hasimplications with respect to the level ofinformation that the planning authority willexpect to accompany the application and alsowith respect to the likely planningdetermination period. The targetdetermination periods for differentapplications are:

• Standard Application – 8 weeks• Major Development - 13 weeks • EIA Development - 16 weeks

The principal national planning policyobjectives associated with waste managementactivities are set out in Planning PolicyStatement (PPS) 10 ‘Planning for SustainableWaste Management’ published in July 2005.Supplementary guidance is also containedwithin the Companion Guide to PPS 10. .Both of these documents can be accessed viathe Department of Communities and LocalGovernment (DCLG) website17.

PPS 10 places the emphasis on the plan ledsystem which should facilitate thedevelopment of new waste facilities throughthe identification of sites and policies in therelevant local development plan. Separateguidance on the content and validation ofplanning applications is also available fromDCLG through their website18. IndividualPlanning Authorities can set out their ownrequirements with respect to supportinginformation and design criteria throughSupplementary Planning Documents linked tothe Local Development Framework. It isimportant that prospective developers liaiseclosely with their Local Planning Authoritiesover the content and scope of planningapplications.

6.2 Key Issues

When considering the planning implicationsof an MBT facility the key issues that willneed to be considered are common to mostwaste management facilities and are:

• Plant/Facility Siting;• Traffic;• Air Emissions / Health Effects;• Dust / Odour;• Flies, Vermin and Birds;• Noise;

22

16 http://www.communities.gov.uk/embeddedindex.asp?id=114571117http://www.communities.gov.uk/index.asp?id=114383418http://www.communities.gov.uk/pub/494/BestPracticeGuidanceontheValidationofPlanningApplicationsPDF326Kb_id1144494.pdf


• Litter;• Water Resources;• Visual Intrusion; and• Public Concern.

A brief overview of the planning context foreach of these issues is provided below.

6.3 Plant Siting

PPS 10 and its Companion Guide containsgeneral guidance on the selection of sitessuitable for waste facilities. This guidancedoes not differentiate between facility typesbut states that:

“Most waste management activities are nowsuitable for industrial locations, many fallwithin the general industrial class in the UseClasses Order.19

The move towards facilities and processesbeing enclosed within purpose designedbuildings, rather than in the open air, hasaccentuated this trend. The guidance goes onto state:

“With advancement in mitigation techniques,some waste facilities may also be consideredas light industrial in nature and thereforecompatible with residential development. Inmore rural areas, redundant agricultural andforestry buildings may also provide suitableopportunities, particularly for themanagement of agricultural wastes”

Mixed waste processing (such as MBT) cantake place in many different buildings at avariety of locations but the following issuesshould be considered:

• MBT processes can be similar in appearanceand characteristics to various processindustries. It would often be suitable to

locate facilities on land previously used forgeneral industrial activities or landallocated in development plans for such(B2) uses;

• Facilities are likely to require goodtransport infrastructure. Such sites shouldeither be located close to the primary roadnetwork or alternatively have the potentialto be accessed by rail or barge;

• The location of such plants together withother waste operations such as MRFs andthermal treatment plants can beadvantageous. The potential for co-location of such facilities on resourcerecovery parks or similar is also highlightedin the Companion Guide; and

• General concerns about bio-aerosols frombiological processing may require an MBTsite to be located away from sensitivereceptors.

6.4 Traffic

Centralised waste facilities will most likely beserved by large numbers of HGVs with apotential impact on local roads and theamenity of local residents. It is likely that thesite layout/road configuration will need to besuitable to accept a range of light and heavy

2319The Town and Country Planning (Use Classes) Order 1987. SI 1987 No. 764


vehicles. Mixed waste processing operationsare designed to split a mixed waste streaminto a number of individual streams some ofwhich are low tonnage or low bulk density.As a result traffic implications may be greaterthan initially considered.

The traffic movements anticipated from a50,000tpa plant would be 20 – 30 refusecollection vehicles per day. This would bereduced if bulk transport systems are used.

6.5 Air Emissions and Health Effects

No studies specifically looking at the healtheffects of MBT facilities have been carriedout. Depending on the nature of anindividual facility, the health effects of MBTfacilities might be expected to be comparableto those of in-vessel composting facilities.

Studies have found no increase in cancer orasthma in populations close to compostingfacilities. There have been public concernsthat open composting facilities could intheory affect the health of people living inclose proximity to the facility. TheEnvironment Agency suggests that riskassessments may be undertaken on siteswhere there are sensitive receptors nearby.Emissions and potential risks to health can bemore readily controlled in an in-vesselcomposting system, or MBT facility.

MBT processes result in the production of afibrous material. This could be recycled ordisposed to landfill as a stabilised wastematerial, or could be burnt as a refuse-derived fuel. Combustion of RDF is subject tothe stringent emission control requirementsof the Waste Incineration Directive and wouldresult in a similar range of emissions to thosefrom the incineration of waste, although thismay well take place at a separate facility tothe MBT process.

6.6 Dust / Odour

Any waste management operations can giverise to dust and odours. The control of odourat MBT facilities needs careful consideration.Because MBT facilities are located within anenclosed building, potential odour emissionscan normally be controlled through thebuilding ventilation system. If there is acombustion element to the facility, odorousair extracted from process areas can be usedin the combustion stage.

If there is no combustion element, the processof air extraction and ventilation willnevertheless dilute odorous air. It may benecessary to disperse extracted air from anelevated point, and/or treat the air.Biofiltration systems can be used to controlodours in air extracted from working areas ifrequired. The need for, and design of odourcontrol systems would need to be assessed ona site-by-site basis.

6.7 Flies, Vermin and Birds

The enclosed nature of MBT operations willlimit the potential to attract vermin andbirds. However, during hot weather it ispossible that flies could accumulate, especiallyif they have been brought in during deliveryof the waste. Effective housekeeping and onsite management of tipping and storageareas is essential to minimise the risk fromvermin and other pests. In some operationswaste heat from the process may be used infresh input waste to bring temperatures tolevels above which flies can live. Similarly,waste storage in some MBT plant is designedto be less that the breeding cycle of verminsuch as rats.

6.8 Noise

Noise is an issue that will be controlled underthe permitting regulations and noise levelsreceived at nearby sensitive receptors can be

24


limited by a condition of a planningpermission. The main contributors to noiseassociated with MBT are likely to be:

• vehicle movements / manoeuvring;• traffic noise on the local road networks;• mechanical processing such as shredders,

screens, trommels and ball mills; and• air extraction fans and ventilation systems.

6.9 Litter

Any waste which contains plastics and paperare more likely to lead to litter problems.With MBT as long as good working practicesare adhered to and vehicles use covers andreception and processing are undertakenindoors, litter problems can be minimised.

6.10 Water Resources

Common to many new waste treatmentprocesses the enclosed nature of theoperations significantly reduces the potentialfor impacts on the water environment. Thegreatest potential for pollution to surface andground water is linked to the arrangementfor delivery of waste and the collection ofprocessed materials.

Pollution of water is unlikely due to MBTfacilities being under cover and rainfall isunlikely to come into contact with theprocess. Even so, any wash down waters orliquid within the waste will need to be

managed using a drainage system on site..This is often cited as being reused within theprocess, but again such process water willneed to be managed.

The level of water usage will be specific tothe technology and therefore it is notpossible to provide detail on the nature ofthe effluent that might be generated andhow it should be managed. However, as partof the permitting requirements for a facility amanagement plan would be required foreffluent.

The case studies on the Waste TechnologyData Centre include an assessment of waterusage.

6.11 Design Principles and Visual Intrusion

The new planning guidance emphasises theimportance of good design in new wastefacilities. Good design principles andarchitect input to the design and physicalappearance of waste facilitates is essential.Buildings should be of an intrinsically highstandard and should not need to be screenedin most cases.

Good design principles also extend to otheraspects of the facility including issues such as:

• Site access and layout;• Energy efficiency;• Water efficiency; and• General sustainability profile

Construction of any building will have aneffect on the visual landscape of an area.Visual intrusion issues should be dealt with ona site specific basis and the following itemsshould be considered:

• Direct effect on landscape by removal ofitems such as trees or undertaking majorearthworks;

25


• Site setting; is the site close to listedbuildings, conservation areas or sensitiveviewpoints;

• Existing large buildings and structures inthe area;

• The potential of a stack associated withsome air clean up systems for mixed wasteprocessing operations may impact on visualintrusion;

• Use of screening features (trees, hedges,banks etc);

• The number of vehicles accessing the siteand their frequency; and

6.12 Size and Landtake

Table 10 shows the land area required for thebuilding footprint and also for the entire site(including supporting site infrastructure,although this is likely to vary greatlydepending on the specific technology usedand the quantities of waste being handled.

Table 10: Landtake estimates for MBT facilities

a Source: Review of Residual Waste TreatmentOptions, 2003, AiIE

b Source: Planning for Waste Management facilities,ODPM, 2004

c Source: Waste Technology Data Centre, 2004

An average MBT plant may have a height of10 – 20m. Some facilities may also have astack if using particular air clean-up systems,potentially increasing overall height. Formore information on landtake for specificwaste management operations, see Defra’sWaste Technology Data Centre.

www.environment-agency,gov.uk/wtd

6.13 Public Concern

Section 7, Social and Perception Issues, relatesto public concern. In general public concernsabout waste facilities in general relate toamenity issues (odour, dust, noise, traffic,litter etc). With facilities which includethermal treatment of the RDF, healthconcerns can also be a perceived issue. Publicconcern founded upon valid planning reasonscan be taken into account when considering aplanning application.

6.14 Environmental Impact Assessment

It is likely that an Environmental ImpactAssessment (EIA) will be required for MBTfacilities as part of the planning process.

Whether a development requires a statutoryEIA is defined under the Town and CountryPlanning (Environmental ImpactAssessment)(England and Wales) Regulations1999. Care should be taken with thedifference in meaning between ‘treatment’and ‘disposal’ when applying theseregulations. A MBT facility is a wastetreatment facility and is not a waste disposalinstallation. The existing additional guidancein DETR circular 02/99 is currently beingrevised. This new guidance is likely to focuson appropriate criteria for establishing needfor EIA and not relate to the general natureof proposals.

26

SizeBuildings

AreaTotal

Landtake

MBT Plant Ab 50,000tpa 3,000m2

MBT Plant Bc 75,000tpa 5,500m2 15,000m2

MBT Plant Cc 0.36 m2/t

MBT Plant Da 140,000tpa 9,000m2

MBT Plant Ea 180,000tpa 35,000m2


For more information on Planning issuesassociated with waste management optionssee Planning for Waste Management Facilities– A Research Study. Office of the DeputyPrime Minister, 2004.http://www.communities.gov.uk/pub/713/PlanningforWasteManagementFacilitiesAResearchStudy_id1145713.pdf

6.15 Licensing/Permitting

If a MBT plant processes over 50 tonnes perday it may be assumed that they will requirea Pollution Prevention & Control (PPC) permitto operate, if processing less than thisquantity a waste management licence wouldbe required. If the process is shown toproduce a fuel (e.g. RDF) rather than a waste,then it would be subject to PPC irrespectiveof the tonnage threshold. The EnvironmentalPermitting Programme (EPP) is due to beimplemented in April 2008 which willcombine waste licensing and permittingsystems.

For more information on licensing &permitting see the Environment Agency site20.

For more information on licensing &permitting see http://www.environment-agency.gov.uk/subjects/waste/?lang=_e

Box 2 illustrates some of the key planningfeatures of the Frog Island MBT facilityoperated by Shanks in the planning authorityof Havering Borough Council.

27

20 http://www.environment-agency.gov.uk/subjects/waste/?lang=_e

Box 2: Frog Island MBT facility

• One of two MBT facilities, 180,000 tpaeach, built for the East London WasteAuthority (ELWA) 25 year PFI wastemanagement contract

• Located on a 4.2 ha site, together with aMaterial Recycling facility (MRF), within theFerry Island Industrial Estate near Rainham

• Site was allocated in the Havering UnitaryDevelopment Plan for light and industrialuses and is surrounded by other industrialusers

• Application submitted January 2003, wentto committee in March and approved withconditions in November 2003

• The Council consulted with the Mayor ofLondon in February who considered theplanning report in July and advised theproposal was acceptable with regard tostrategic planning policy

• To meet the condition that it isaesthetically pleasing from the RiverThames, the facility has timber cladding

• Refuse derived fuel produced from theFrog Island facility will be processed by theproposed nearby Novera Gasificationfacility, which was granted planningpermission in October 2006

7. Social and perception issues

This section contains a discussion of the socialand public perception considerations of MBTfacilities.

7.1 Social Considerations

Any new facility is likely to impact on thelocal residents and may provide both positiveand negative impacts. Potential impacts onlocal amenity (odour, noise, dust, landscape)are important considerations when siting anywaste management facility. These issues areexamined in more detail in the PlanningSection of this brief. Transport impactsassociated with the delivery of waste andonward transport of process outputs may leadto impacts on the local road network. ThePlanning and Permitting section of thisdocument provides an estimate of potentialvehicle movements.

An MBT facility may also provide positivesocial impacts in the form of employmentopportunities and educational opportunities.Typical employment for a MBT plant of50,000tpa capacity would be 2 – 8 persons atany one time (more if manual pickingoperations are used). The plant may beoperated on a shift system, for example toallow for 24 hour operations. Many newfacilities are built with a visitors centre toenable local groups to view the facility andlearn more about how it operates.

7.2 Public Perception

Recent changes in waste managementarrangements in many areas has raised theprofile of municipal waste services. Manypeople as a result of greater publicity andtargeted education are now embracing theneed for waste reduction, recycling and to alesser extent the need for new waste facilities.The wider perception of waste facilities as abad neighbour will take longer to overcome.New waste facilities of whatever type arerarely welcomed by residents close to wherethe facility is to be located.

Public opinion on waste management issues iswide ranging, and can often be at extremeends of the scale. Typically, the most positivelyviewed waste management options for MSWare recycling and composting. However, this isnot necessarily reflected in local attitudestowards the infrastructure commonlyrequired to process waste to compost, or sortmixed recyclables. It should be recognisedthat there is always likely to be someresistance to any waste management facilitywithin a locality.

28

7. Social and perception issues

At present there is a relatively low level ofunderstanding of the concept of MBT by thepublic. In public consultations thesetechnologies scores inconsistently whenexplained in detail as a residual wastetreatment technology.

Two examples of public consultationshighlighting the diversity of opinion withregard to MBT are illustrated in Box 3, below.

Overall, experience in developing wastemanagement strategies has highlighted theimportance of proactive communication withthe public over waste management options.The use of realistic and appropriate models,virtual ‘walk – throughs’ / artists impressionsshould be used to accurately inform thepublic. Good practice in terms of publicconsultation and engagement is an importantaspect in gaining acceptance for planning anddeveloping waste managementinfrastructure. Defra is funding thedevelopment of small to medium scaledemonstration plant in England for localauthorities to visit and for Defra to publishdata on performance. For more informationcontact [email protected].

29

Box 3: Public consultation on MBT

A public consultation in an area of Walesresulted in a clear preference that any wastethat could not be recycled or compostedshould be dealt with through MBT.Respondents felt that an MBT-led strategy wasa positive approach for residual waste whetherit aims to achieve or exceed diversion targets.

Conversely, a large scale public consultation inan area of England revealed the oppositereaction with MBT being the least favouredapproach of the residual waste treatmentoptions.

8. Cost

The cost of constructing, operating andmaintaining MBT facilities are addressedusing a common cost model on Defra’s WasteTechnology Data Centre. Both capital andoperating costs are included on specifictechnologies which may be used for thepurposes of indicative comparisons ratherthan accurate reflections of actual costs. Thetable below shows indicative capitalexpenditure (Capex) and operationalexpenditure (Opex) for aerobic and anaerobicMBT facilities. There are a wide range of costsdependent upon the complexity of thetechnology and the degree of mechanisationand automation employed.

Table 11: Typical MBT cost using Anaerobicand Aerobic processes

Sources: Waste Technology Data Centre 2007 andJuniper Consultancy Services (2005) MechanicalBiological Treatment: A Guide for Decision MakersProcesses, Policies and Markets

These costs provided are predominantly basedon European examples. Costs in the UK willinvolve differing site specific issues such aspermitting, labour, emission controls andother requirements.

It should also be noted that MBT systems aresensitive to the markets and outlets forrecycled materials, RDF and soil conditionersthat are produced by different processes. It islikely that many of the material outputs fromMBT will have a negative value and these arenot included in the above costs. The impactof the markets/outlets for these materials isnot reflected in the costs provided, nor is thecost associated with the landfill of anyresidues should a market fail to emerge.Partnerships between MBT operators andpotential users of outputs should beestablished at the earliest opportunity andcare should be taken to ensure plant candeliver materials of sufficient quality for therequired market outlet.

It is vital in any negotiation, that there is atrue appreciation of the cost of essentialrepairs and refurbishment. Additionally theundeveloped markets/outlets (and risksassociated with loss of markets) for products /outputs of these processes needs to bereflected in cost models. Any building shouldhave sufficient capacity to house newseparation equipment. The above costs arealso not the same as the price a LocalAuthority may pay for a treatment service,which will also include other factors such asfinance costs and profit margins.

For cost information on examples of differentprocesses see Defra’s Waste Technology DataCentre www.environment-agency.gov.uk/wtd

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Aerobic processes AD processes

CapacityCapex£/t/yr

Opex£/t

Capex£/t/yr

Opex£/t

<50,000 70 – 150 up to 140 160 – 420 From 23

>50,000 28 – 225 20 – 69 107 – 278 16 – 69

9. Contribution to national targets

9.1 Recycling

Recyclate derived from a MBT plantprocessing household waste qualifies for BVPI82a (Recycling) at the point at which it leavesthe plant to be sent to the reprocessor. Thematerial must pass to the reprocessor (andnot be rejected for quality reasons) to countas recycling. The same would also apply toglass used as an aggregate. It should benoted that some materials may have marketlimitations due to being derived from a mixedMSW source. For example British Standard BSEN 643 states that ‘Recovered paper fromrefuse sorting stations is not suitable for usein the paper industry.’ Although this standardis not legally binding, it is supported by themain trade associations for the paperrecycling sector.

The Government has recently increasednational recycling and composting targets forhousehold waste through the Waste Strategyfor England 2007. Targets are at least 40% by2010, 45% by 2015 and 50% by 2020. Formore information on the contribution of MBTto Best Value Performance Indicators andrecycling see the local authority performancepages on the Defra website

http://www.defra.gov.uk/environment/waste/localauth/perform-manage/index.htm andhttp://www.wastedataflow.org/Documents/BVPI%20FAQs.pdf

9.2 Composting

Compost generated through the processingof source segregated organic material by in-vessel composting will contribute to BVPI 82b,the indicator for the amount of composting alocal authority has achieved. The definition ofBVPI 82b now also includes waste which hasbeen treated through a process of anaerobicdigestion.

Where MBT processes are configured toproduce an organic rich stream known as anCLO from mixed residual MSW to be utilisedas a low grade soil conditioner for example,this material may (but is ‘unlikely to’) qualifyas composting under BVPI 82b. The CLO couldbe utilised in applications such as brownfieldrestoration, landfill restoration or some bulkfill uses (provided that the appropriateengineering and quality standards are met).

These materials will only qualify as‘composted’ under the Best ValuePerformance Indicator (BVPI 82b) if theoutput meets the appropriate criteria for usein the intended application. Some wastemanagement contractors have demonstratedthat there is a market for these materials,however the current Best Value PerformanceIndicator Guidance (as of November 2004)states the criteria for composting should be ‘aproduct that has been sanitised andstabilised, is high in humic substances, andcan be used as a soil improver, as aningredient in growing media or blended toproduce a top soil that will meet BritishStandard BS2882 incorporating amendmentno.1…’ It also states that it is ‘unlikely thatproducts of a Mechanical BiologicalTreatment process will meet this definition.’However if the definition could be achievedthen the product would qualify as BVPI 82b.

9.3 Landfill Allowance Trading Scheme(LATS)

The European Landfill Directive and the UK’senabling act, the Waste & Emissions TradingAct 2003, require the diversion ofbiodegradable municipal waste (BMW) fromlandfill. MBT processes have the potential todivert BMW from landfill. Any outputs thatare recycled, used as soil conditioner (underan exemption) or burnt as RDF and which are

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not landfilled will count directly towardsdiversion targets. The ability of MBT to meeta high level of landfill diversion will thereforedepend upon the availability of markets oroutlets for the outputs, and the quality of theprocess outputs.

However, MBT plant can also be used to bio-stabilise waste prior to landfilling. In this casebiological treatment is used to reduce thewaste’s potential to degrade and producemethane once landfilled. The EnvironmentAgency (EA) has developed a methodology todetermine the ‘stability’ or ‘biodegradability’of any outputs from an MBT plant which aresent to landfill. This methodology can beused to determine the actual amount ofbiodegradable material being landfilled. Thisinformation could help an authority achieveallowance allocations under the LandfillAllowance Trading Scheme (LATS). Thetesting is not a statutory requirementcurrently. Detailed guidance on how thediversion of biodegradable waste is measuredin MBT processes can be found on theEnvironment Agency website:

http://www.environment-agency.gov.uk/commondata/acrobat/mbt_1154981.pdf

As any MBT plants developed in the UK arelikely to vary in their method of operation,the stability test is likely to be applied to eachMBT plant on a regular basis. Up to dateinformation can be obtained from Defra’sLATS information webpage:

http://www.defra.gov.uk/environment/waste/localauth/lats/index.htm

As the requirements of the Landfill Directiverelate to the amount of biodegradablematerial landfilled, the stability of materialsdiverted from landfill via MBT will not needto be measured.

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Main Heading

9.4 Recovery

MBT technologies will only contributetowards recovery targets through the wastestreams that are sent to an energy recoveryprocess. This may be either RDF combusted ordegraded in a thermal plant (e.g .Incinerationwith Energy Recovery, Advanced ThermalTreatment or co-combusted in a Cement Kiln),or the biological stream that is processed inan Anaerobic Digestion plant (see the specificguidance for BVPI 82c and also 82b for AD).The Government has recently increasednational recovery targets for municipal wastethrough the Waste Strategy for England 2007.Targets are 53% by 2010, 67% by 2015 and75% by 2020. For more details see

http://www.defra.gov.uk/environment/waste/localauth/perform-manage/index.htm

9.5 Renewables

The Renewables Obligation (RO) wasintroduced in 2002 to promote thedevelopment of electricity generated fromrenewable sources of energy. The Obligationrequires licensed electricity suppliers to sourcea specific and annually increasing percentageof the electricity they supply from renewablesources, demonstrated by RenewablesObligation Certificates (ROCs). The targetcurrently rises to 15.4% by 2015/16. Inessence, the RO provides a significant boostto the market price of renewable electricitygenerated in eligible technologies.

Electricity generated from the biomass(renewable) fraction of waste (including RDF)in ‘advanced conversion technologies’(including AD, gasification and pyrolysis) orincineration plant with good quality heat andpower is eligible for support under the RO.This can provide an important additionalrevenue stream for a proposed plant, as longas it meets the qualifying requirements. Asthe value of a ROC is not fixed, the long termvalue would need to be assessed in detail todetermine its overall financial value to theproject.

The Department for Industry (DTI) isconsidering providing greater support totechnologies producing renewable energyand assessing methods for removing barriersto renewable energy generation.

Up-to-date information regarding RDF andROCs can be obtained from the DTI website

www.dti.gov.uk/energy/sources/renewables/index.html.

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34

10. Further reading and sources ofinformation

WRATE (Waste and Resources Assessment Tool for the Environment)

http://www.environment-agency.gov.uk/wtd/1396237/?version=1&lang=_e

The Waste Technology Data Centre

www.environment-agency.gov.uk/wtd

New Technologies Demonstrator Programme [email protected]

Defra New Technologies website,

http://www.defra.gov.uk/environment/waste/wip/newtech/index.htm

Integrated Pollution Prevention and Control, Draft Reference Document on Best AvailableTechniques for the Waste Treatments Industries, European Commission – Directorate GeneralJoint Research Centre, January 2004

Refuse Derived Fuel, Current Practice and Perspectives (B4-3040/2000/306517/Mar/E3), EuropeanCommission – Directorate General Environment, July 2003

Local Authority funding

http://www.defra.gov.uk/environment/waste/localauth/funding/pfi/index.htm

The Local Government PFI project support guide

www.local.odpm.gov.uk/pfi/grantcond.pdf

For Works Contracts: the Institution of Civil Engineers ‘New Engineering Contract’

(available at www.ice.org.uk).

For large scale Waste Services Contracts through PFI and guidance on waste sector projects seethe 4ps, local government's project delivery organisation

http://www.4ps.gov.uk/PageContent.aspx?id=90&tp=Y

Planning for Waste Management Facilities – A Research Study. ODPM, 2004

http://www.odpm.gov.uk/stellent/groups/odpm_planning/documents/page/odpm_plan_030747.pdf

AiIE Ltd, 2003, Review of residual waste treatment technologies, Report prepared on behalf ofKingston upon Hull City Council and East Riding of Yorkshire Council

http://www.eastriding.gov.uk/environment/pdf/waste_treatment_technologies.pdf

The Additional Paper to the Strategy Unit, Waste Not Want Not study, ‘Delivering the LandfillDirective: The Role of New & Emerging Technologies’, Dr Stuart McLanaghan

http://www.number10.gov.uk/files/pdf/technologies-landfill.pdf

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11. Glossary

Aerobic In the presence of oxygen.

AerobicDigestion/Composting

Biological decomposition of organic materials by micro-organisms under controlled,aerobic, conditions to a relatively stable humus-like material called compost.

Anaerobic In the absence of oxygen.

Anaerobic Digestion A process where biodegradable material is encouraged to break down in theabsence of oxygen. Material is placed in to an enclosed vessel and in controlledconditions the waste breaks down typically into a digestate, liquor and biogas.

Animal By-ProductsRegulation

Legislation governing the processing of wastes derived from animal sources.

Biodegradable Capable of being degraded by plants and animals.

Biogas Gas resulting from the fermentation of waste in the absence of air(methane/carbon dioxide).

Biodegradable MunicipalWaste (BMW)

The component of Municipal Solid Waste capable of being degraded by plants andanimals. Biodegradable Municipal Waste includes paper and card, food and gardenwaste, and a proportion of other wastes, such as textiles.

Co-combustion Combustion of wastes as a fuel in an industrial or other (non waste management)process.

Digestate Solid and / or liquid product resulting from Anaerobic Digestion.

Feedstock Raw material required for a process.

Floc A small loosely aggregated mass of flocculent material. In this instance referring toRefuse Derived Fuel or similar.

Greenhouse Gas A term given to those gas compounds in the atmosphere that reflect heat backtoward earth rather than letting it escape freely into space. Several gases areinvolved, including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O),ozone, water vapour and some of the chlorofluorocarbons.

Green Waste Waste vegetation and plant matter from household gardens, local authority parksand gardens and commercial landscaped gardens.

Incineration The controlled thermal treatment of waste by burning, either to reduce its volumeor toxicity. Energy recovery from incineration can be made by utilising the calorificvalue of the waste to produce heat and / or power.

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11. Glossary

In-vessel Composting The aerobic decomposition of shredded and mixed organic waste within andenclosed container, where the control systems for material degradation are fullyautomated. Moisture, temperature, and odour can be regulated, and stablecompost can be produced much more quickly than outdoor windrow composting.

Materials Recycling Facility/

Material Recovery Facility(MRF)

Dedicated facility for the sorting / separation of recyclable materials.

Mechanical BiologicalTreatment (MBT)

A generic term for mechanical sorting / separation technologies used in conjunctionwith biological treatment processes, such as composting.

Municipal Solid Waste(MSW)

Household waste and any other wastes collected by the Waste Collection Authority,or its agents, such as municipal parks and gardens waste, beach cleansing waste,commercial or industrial waste, and waste resulting from the clearance of fly-tipped materials.

Recyclate/Recyclablematerials

Post-use materials that can be recycled for the original purpose, or for differentpurposes.

Recycling Involves the processing of wastes, into either the same product or a different one.Many non-hazardous wastes such as paper, glass, cardboard, plastics and scrapmetals can be recycled. Hazardous wastes such as solvents can also be recycled byspecialist companies.

Refuse Derived Fuel (RDF) A fuel produced from combustible waste that can be stored and transported, orused directly on site to produce heat and/or power.

Renewables Obligation Introduced in 2002 by the Department of Trade and Industry, this system creates amarket in tradable renewable energy certificates (ROCs), within each electricitysupplier must demonstrate compliance with increasing Government targets forrenewable energy generation.

Solid Recovered Fuel Refuse Derived Fuel meeting a standard specification, currently under developmentby a CEN standards committee.

Source-segregated/

Source-separated

Usually applies to household waste collection systems where recyclable and/ororganic fractions of the waste stream are separated by the householder and areoften collected separately.

Statutory Best ValuePerformance Indicators

Local Authorities submit performance data to Government in the form of annualperformance indicators (PIs). The Recycling and Composting PIs have statutorytargets attached to them which Authorities are required to meet.