waste characterisation literature review

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Waste Characterisation Literature Review.

Copyright of LabSearch, a working title of Dr Malcolm Sutherland 2013

BE-AWARE Work Package 3 Deliverable 3.3

WASTE CHARACTERISATION LITERATURE REVIEW

Mohamed Osmani, Andrew Price, Malcolm Sutherland

(Loughborough University)

Completed November 2006

REVISED MAY 2013:portions of the original document have been scanned


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Executive Summary

This report was completed in fulfilment Deliverable 3 of Work Package 3, of the BE-AWARE

protect. The report reviews waste characterisation approaches, technologies andmethodologies, and also discusses the requirements for the next stage of Work Package 3.

The identification and characterisation of waste materials can be a convex task, requiring

careful attention of varying quantises, flows, and the chemical and physical composition

Available data may be limited, and studies into a waste stream rely on representative

sampling, interviews, and the use of resources such as IT databases or models. The potential

for recycling a waste material is also limited by financial costs such as transportation, and

the availability of appropriate reprocessing technologies.

The following approaches of waste characterisation are discussed:

classification: waste materials are generally classified into groups of similar items, such as

plastics, wood, bricks, etc.;

quantification: waste streams and materials are quantified, by observations or sampling,

by interviews or questionnaires, or by simplifying data (for a few sites) for a larger sector or

region;

composition: waste stream components are studied for their chemical and physical

composition, in order to identify any hazardous chemicals or contaminants, or to assess

their suitability for recycling;

economic aspects: the viability of recycling a material is determined by a range of financial

costs, including haulage, capital costs (e.g. purchasing machinery), market value and

environmental taxes; and,

performance: the potential for recycling a material is also governed by its performance-

related properties, including durability, purity, safety and physical stability,

Waste characterisation arid recycling depends on the use of technological tools, including

computer models and databases, and laboratory instruments. Computer databases can be

used to assemble and organise extensive data, which can be altered and updated. One

important use of a database is to list companies which are producing recycled products, in

order to expand the market. Another use is for determining the environmental impact of

materials through database-generated results. Computer modelling can be used to study

complex processes (such as the transfer of materials and wastes within an industrial sector),

and to predict future scenarios (e.g. the changes to financial costs affecting a company if

more materials are recycled). Assessment of waste materials can also be performed in the

laboratory, e.g. to analyse for hazardous chemicals, and to correlate results with legislative

requirements.


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Three methodologies used in waste characterisation include sampling techniques, analytical

techniques, and the marketing of recycled products. Sampling of waste materials or streams

can involve collecting actual samples, or collecting in-formation through interviews and

questionnaires. Both methods have disadvantages, e.g. errors can arise from cross-

contamination of actual materials; or an interviewee's incomplete knowledge of the

materials. The accuracy of data collected through sampling is also limited by time, cost and

accessibility to information or the materiaIs. The reliability of waste material analysis can be

affected by contamination of the equipment, and by the precision of the data produced.

In order for a recyclable material to penetrate the market at a profit, the properties of the

material need to be compared with those produced by competitors (especially raw

materials). Marketing a recycled material includes surveying customers' opinions;

establishing its market value; assessing the level of competition in the market, and

examining all the costs involved in producing and selling the material.


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CONTENTS

1: Introduction pages 5 - 6

1.1: Background

1.2: Aims and objectives

2: Waste characterisation techniques pages 7 - 19

2.1: Introduction

2.2: The definition of Waste Characterisation

2.3: Construction and Demolition waste in the UK

2.4: Quantification

2.5: Classification

2.6: Composition

2.7: Economic aspects

2.8: Performance aspects

3: Waste characterisation technologies pages 20 - 26

3.1: Introduction

3.2: Databases

3.3: Modelling

3.4: Assessment

4: Methodologies pages 27 - 33

4.1: Sampling strategy

4.2: Analytical methodology

4.3: Marketing

5: Conclusions and further work pages 34, 35

5.1: Summary of findings of the literature review

5.2: Further work

References pages 36 - 41


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1: INTRODUCTION

1.1: Background

This report comprises a literature-based investigation into waste characterisation

approaches, technologies and methodologies, as part of Be-Aware Work Package 3. The

alms behind Work Package 3 are to develop a detailed knowledge of the types and

properties of construction wastes, to investigate their viability tor recycling, and to create a

pan-industrial waste exchange. Previous Work Package 3 tasks focussed on targeting,

prioritising and mapping waste products across a number of construction sectors. Research

for Work Package 3 completed to date is summarised below:

Figure 1: completed Be-Aware WP3 project tasks

Construction waste targeting, prioritising, and mapping activities provided insights into the

existing nature of construction waste material recycling in the UK, and highlighted the key

barriers associated with waste materials' recycling options. The range of construction waste

materials and the significance of some waste streams were identified. The next stage in the

Be-Aware project was to gain an understanding of the aspects and methods used in

characterising waste. This was accomplished through the collection and review of related

literature, the findings of which are summarised in this report.

1.2: Aims and objectives

The aim of this report is to review existing waste characterisation strategies and techniques.

The main objectives are to examine current approaches, technologies and methodlogies.

These are summarised in Figure 2, and discussed throughout the report. Finally, the mainfindings are summarised and linked with the next stages in Work Package 3 or the Be-Aware


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project. This report also contains recommendations on which waste characterisation issues

need to be further investigated, through a waste characterisation survey, and at Workshop

2 (Waste Performance and Economic Assessment) (held in February 2007).

Figure 2: aspects of waste characterisation examined in the literature review


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2: WASTE CHARACTERISATION APPROACHES

2.1: Introduction

This chapter discusses the types of Information which need to be collected for a waste

characterisation study, The characterisation of waste streams and the estimation of waste

flow rates is essential, due to increasing penalties for waste disposal (to landfill), and

increasing opportunities in recycling (Gay et al, 1997).

To acquire such information, a systematic assessment of waste streams must be

undertaken, using different approaches. Waste streams need to be quantified e.g. to assess

if generated wastes are abundant enough to be reprocessed (John and Zordan, 2000). The

composition of a waste is usually compared with required standards detailed in industrial

manuals (e.g. British standards). In addition, economic and performance data (e.g. marketvalue of recycled products, durability of materials) may be collected in order to assess

whether or not a recycling strategy may be viable.

2.2: Definition of waste characterisation

Yu and MacLaren (1995) defined waste characterisation as the analysis of the composition of

the waste stream by material types (such as glass, paper. metal, etc.), or by product types

(such as glass containers, magazines, cans, etc.). Moore et al(1998) stated that, "in order to

describe waste, two concepts are required: waste stream amounts and the composition ofthese waste streams. They also stated that waste characterization involves analysing the

waste itself; the related construction products on the marvel; and the products of waste

reprocessing. Waste characterisation studies can be linked with developing or choosing

recycling technologies, and identifying waste materials which can be recovered reprocessed,

and sold on the market (Peng et al, 1997).

2.3: Construction and demolition waste in the UK

Construction and Demolition Waste (C&DW) is the largest waste stream being produced inthe UK, amounting to over 100 million tonnes per annum (Smartwaste, 2006), and

accounting for over 30% of all waste produced in 2004 (DEFRA, 3005). It is also proving to be

one of the most potentially recyclable. Halliwell (2006) reported that in 2000, approximately

48% of C&D waste was recycled; another 43% was beneficially re-used; and the remaining

4% was sent to landfill. Several initiatives have been undertaken in recent years by the UK

government and by companies to exploit and re-use a range of materials present in C&DW.

It is not precisely known what quantities of each type o+ waste material are produced

throughout the UK. Data compiled by Poon et al(2004) (Figure 3) detailed the percentage of

ordered construction materials for a British case study (office block) construction project

ending up as waste. As much as 30% of purchased material (namely plywood and


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plasterboard) may leave the construction site as waste, Chen et al (2002) provided more

modest predictions, estimating that on average, between 2.5% and 6.0% mass of bricks,

blocks, drywall, tiling and wood brought onto British construction sites end up being

discarded.

Figure 3: percentages of ordered materials being discarded (by mass) (Poon et al, 2004)

2.4: Quantification

Producing quantified waste data

There are two general approaches in quantifying waste (USEPA, 1996):

- Source-specific: the individual components of a waste stream being sampled, sortedand weighed: and,

- Material flows method: the collection of data on the rate of production of(combined) wastes and/or saleable products from an operation, and using this to

predict individual quantities.

Waste quantification may yield data with wide error margins (USEPA. 1996). The source-

specific approach might be applicable within a small manufacturing plant, although the data

produced may only be relevant to the plant itself, and should not be applied to other

manufacturing sites. When predicting the quantities and flow-rates of waste streams across

a sector (e.g. concrete production) or geographical area (e.g. England), using quantified data

can produce strongly shewed atypical results (USEPA, 1996). The scope of waste

quantification data is generally limited by the geographical area of study, the particle

size/shape of the material, and by the desired precision o1 results (Yu and MacLaren, 1995).


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Units of waste measurement

Researchers can use a wide variety of units for quantifying waste. Four reported examples

include (Ekanayake and Ofori, 2004):

- percentage per total waste generated;- percentage per total amount of purchased material (e.g. no. of tonnes of spent

concrete mix per tonne of raw materials);

- amount of waste generated at a particular financial cost; and,- mass of waste generated per square metre (e.g. on a building site).

Waste stream quantity and flow techniques

Measuring the quantity and components of a waste stream will require same site

measurements, an audit into the quantities of raw materials ordered by a

manufacturer/contractor (e.g. checking order documents}, and making general predictions{e.g. using computer-aided tools/models). At best, such data is often speculative (USEPA,

1996), although general patterns (i.e. which is the largest waste stream) can be deduced-

Table 1 summarises the three general techniques used for quantifying waste streams:

Table 1: Possible activities undertaken a qualifying waste

General approaches Activities

Sample collection/study - visual characterisation (observation, estimation)- collecting representative waste samples on site- tracking number of waste carrier vehicles (e.g. number of trucks

transporting waste to landfill)

Contacting/reviewing companies - questionnaires with managers, engineers, etc.- investigating documents (purchases, sales, costs of waste

disposal/removal)

- reading environmental reports produced in-houseDatabase, model - collecting geographical data (e.g. number of companies in

specified region)

- using conversion factors (e.g. amount of waste produced perunit of product sold)

Gay et al, 1993; Yu and MacLaren, 1995; CGS (Gore & Storrie) Ltd, 2000; ESA Association, 2005; Govt of Canada, 2005;

Cascadia Group, 2003; Duran et al, 2006; Envirowise, 2006

Sample collection and inspection

Sample-based studies can be performed by selecting a random and representative sample

of waste that may be directly measured, for example by calculating the mass or volume per

disposal truck or container, or even using a large weighing balance (Moore et al, 1995;

Engineering Solutions and Design Inc, 2004). IT necessary a waste sample can be crushed,


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sieved, dried, etc. prior to weighing, in order to generate a reliable measurement, or to

separate out specific waste fractions from a mixture (La Cour-Jansen et al, 2004).

When measuring waste streams in a broader sense (e.g. industry-wide), general

assumptions may need to be made. Cascadia Group (2006) noted that visual estimates of

waste production are commonly used, whereby the approximate mass or volume of a

material can be recorded by observing how many truck-loads of the material are being

collected. Bulk density values of specific materials may be used to convert volume-based

units into mass-based units; however, field tests conducted by CGS3 (Gore & Storie) Ltd

(2000) revealed that actual densities of demolition waste could differ significantly from

predicted average values.

Contacting companies and reviewing records

Information on quantities of waste arising within a manufacturing plant may be collected

through reading company environmental reports, interviewing managers, or sending outquestionnaires to companies. These sources of data in turn may be derived from records of

ordered materials (i.e. purchase orders); payments to waste disposal contractors (receipts,

account books); and the recorded number of finished products purchased, sold or

transported on and off the site (Envirowise, 2006).

Using databases and models

Waste production data may be entered into a computer database or model, based on the

assumption that the quantities of waste materials emerging from a region relates to the

density and number of relevant companies or sites (Govt. of Canada, 2005). If anapproximate quantity of waste produced per unit of usable product is specified, the total

production' of waste in a region may be calculated by examining the total sales or purchases

made by a company (Gay et al, 1993).

2.5: Classification

Waste characterisation reports often include tables of waste material groups or clusters.

Table 2 over-page lists a few examples of categories used by researchers in the field.

The defining properties of materials in a category determine how they can be analysed or

reprocessed. For example, certain plastics are generally hydrophobic and lightweight, and

can be separated from a waste stream by floatation (i.e. the selected plastic items float

whilst the rest of the waste sinks (Peng et al, 1997, Pascoe, 2003).


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Table 2: general categories of waste

2.6: Composition

Waste composition studies differ from quantification studies, whereby sampling and

analysis of materials is mandatory. It is usually more costly and time-consuming to

determine the precise composition of a waste material or waste stream throughout a region

or sector (USEPA, 1996). Nevertheless, the composition must be taken into account in order

to (Sfeir et al, 1999):

estimate the material recovery potential for recycling;

identify suitable or valuable components or chemical constituents;

aid in designing and selecting reprocessing equipment;

examine the chemical, physical, biological and thermal properties of the waste

material/stream; and,

comply with environmental, H&S and industrial standards.


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Material recovery and proportions

Several waste characterisation studies reviewed contained tables, listing a wide range of

materials found m sampled waste streams, and indicating their proportions (CG&S (Gore &

Storie), 2000; DTLR, 2002; ESA Association, 2005; Govt of Canada, 2005; Cascadia Group,

2006; Duran et al, 2006). The recycling potential of a waste stream is governed by (CIRIA,

2004):

ease ofrecycling specific materials;

degree of segregation/purity of materials; and,

prevailing market value ofrecycled products.

Not every substance or material in a waste stream may be suitable for recycling, and of

those which are, the viability of recycling or re-use can vary significantly (CIRIA, 2004). The

proportions of different substances or materials within a waste stream need to be identified

in order to prioritise which materials should be separated and reprocessed. A materialwhich forms a minor contribution to the waste stream is probably less economical to isolate

and recycle, unless it is pure and carries a high marker value.

The potential market value of similar materials can vary greatly: for example, recycled

ferrous metals may sell for between 3 and 30 per tome, whereas non-ferrous metals, (e.g.

brass) could sell for up to 1500 per tonne (CIRIA, 2004). Even the same materials can vary

greatly in value, based on its chemical or physical composition; for example, reasonably

pure steel scrap is much lower in value than stainless steel (CIRIA, 2004). Only specific

materials can be obtained from a particular recycling procedure. An example is the use of a

magnet to remove ferrous metal scrap; other metals such as aluminium are non-magnetic(Forton et al, 2006).

Selection of re-processing equipment

It is important to know the composition of the waste stream, including physical composition

such as particle size distribution, in order to select and design the reprocessing equipment.

For poorly sorted demolition rubble, a wide range of screens or sieves may be used to

separate the material into several different particle size fractions (Peng et al, 1997).

Peng et al (1997) detailed the methods used for segregating and reprocessing differentfractions from demolition waste (Figure 4 over-page). A mixture of soil, concrete/clay brick

rubble, plastics and wood has no value unless the individual materials can be analysed, and

thereafter separated and treated.

Examination of waste material properties

A composition study of a waste should be as complete as possible. In spite of

environmental legislation or internal waste management strategies, companies or

contractors producing wastes may not have fully analysed their waste streams, and further

sampling and analyses may therefore be required. Waste material properties which shouldbe examined are summarised in Table 3 over-page (John and Zordan. 2000).


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Figure 4: an illustration of separating waste fractions and recycling routes (Peng et al, 1997)

Table 3: waste material composition properties (John and Zordan, 2000; Stagenberg et al, 2003)

2.7: Economic Aspects

The recycled materials market is in competition with the raw materials market, although

environmental legislation has altered the market in recent years (e.g. imposing tariffs on

raw materials, e.g. aggregates), it is difficult to accurately predict the economic costs and

benefits of recycling, compared with raw material production and disposal to landfill

(European Commission, 2000). Even if recycling a material is possible, the process may beprohibitively expensive, and can lower the market value (Calcott and Walls, 2005).


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Recycling costs

Before a waste material can be reprocessed, a wide spectrum of internal and external costs

must be investigated. Once the waste itself has been analysed, the equipment and

procedures required for recycling may be considered. These in turn carry financial costs,

which are listed in Table 4:

Table 4: Economic costs to be considered in designing a recycling process

(Witburn and Goonan, 1998; Wie et al, 2003)

Limiting factors

The exact profit margins involved in recycling a specific material vary greatly and is highly

depend on manufacturer plants/construction sites, locations, settings (e.g. rural or urban),

the value of the material itself. Although the profitability of recycling differs between

company sites, some general trends should be considered in an economic study.

Setting

The viability of recycling may vary between rural and urban regions. For example, recycling

is more profitable in an urban location for the recycling of aggregates for the following

reasons (Wilbum and Goonan, 1998):

building projects are more numerous and greater in size;

natural aggregate sources (i.e. quarries) are distant;

waste disposal costs to landfilI are generally higher; and,

there is often stricter environmental or H&S regulation on-site, due to a greater density of


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exposed persons nearby.

Economies of Scale

It is widely perceived that the larger the recycling facility (and the greater its capacity), the

better the profit margin. On the other hand, an extensive recycling operation relies on a

copious and regular supply of a waste material. The ideal situation is therefore to recycle a

copious supply of waste material at a constant rate (Wilbum and Goonan, 1998). This is

seldom possible with a wide range of construction materials, particularly those arising from

construction/demolition sites.

Generally small quantities of wastes are generated at each construction material

manufacturing plant throughout the UK; The waste might not be able to be adequately

stored on-site due to restricted space, and health 5 safety regulations (e.g. fire risk

mitigation); Halliwell (2006) suggested that the centralised storage depots for construction

wastes could be created, where wastes from several local manufacturing plants could becollected, and then sent to recycling centres.

Distance

The distance between waste sources and reprocessing plants is a strong governing factor

behind recycling viability. Waste haulage fees [based on quantities and mileage) therefore

need to be estimated (Wie et al, 2003). Where possible, site contractors and products

manufacturers will aim to minimise waste production In-situ, or re-use the product in house

and on-site.

Resources

Recycling a specific waste material will only be profitable if the appropriate equipment is

accessible, there is adequate land or space, and the employees adequately framed and/or

skilled. Additionally, administrative costs (e.g. of recruiting staff), and the depreciation of

selected equipment {e.g. working lifetime, maintenance) need to be considered. The costs

{and space required) of having the waste material properly stored prior to recycling should

also be examined (Wie et al, 2003).

Government intervention: taxation and incentives

The imposition of environmental taxes is practised by several governments worldwide. In

the UK, a range of measures have been taken during the past decade, some of which are

listed in Table 5 over-page. State incentives are also being used in the UK to further the

development of markets for recycled products. In recent years, some construction

companies producing aggregates have received capital grants funding from WRAP, which

were invested in machinery and testing programmes for producing recycled aggregates

(WRAP, 2005).


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Table 5: examples of environmental tax measures in the UK (Halliwell, 2006; Osmani and Li, 2006)

Predicting economic costs

Construction waste management entail a wide range of activities and essential goods, air of

which incur financial costs. Yahya and Boussabaine (2006) summarised these under the title,

"Eco-costs", which are reproduced below:

Recycling and reprocessing waste materials can yield financial benefits in addition to

environmental Improvements. The balance of economic costs and benefits of recycling were

summarised by Begum et al, (2006), and reproduced below:

Although some of these costs such as reduced noise are intangible, the emissions andimpact of recycling operations is nowadays matched by the cost of environmental taxes, and


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installing safety equipment. It is normally assumed that a recycling operation will be

conducted over several years. When predicting costs spanning a few years or longer, two

essential variables to consider are: (i) the rate of inflation; and, (ii) the fluctuating market

value of products/materials.

From these, one may be able to predict the Return-On-Investment on the project (i.e. how

long it will take to pay off the debts incurred by investment). There are various methods and

equations, which could be used for this, although resulting data should be interpreted with

caution. One example is Average Cost Estimation, which is the total costs incurred in a given

period, divided by the quantity of products produced (e.g. cost per tonne); this does not

take into account fixed and variable costs, nor does it consider variable rates of production

activity (Stenis, 2000).

2.8: Performance aspects

The viability of recycling a material is dependant on the quality of the product being sold,

and on the ease and competence of the recycling process. There is also the possibility of

lending a waste malarial into a batch of raw material. With plastic materials, this is often the

case, since purely recycled plastic is often of a lower market value (Smith, 2001).

Performance criteria

Key performance aspects to consider for potential waste recycling include (CIRIA, 2000):

origin of material; uniformity of material quality;

potential tor degradation;

potential far swelling;

deleterious matter and contaminants;

drainage characteristics, and;

susceptibility to frost.

Recovering waste materials

Most composite building materials are bespoke in their design, and are therefore rarely re-

used for the same purpose, since it may be difficult to re-calculate their load-bearing and

other physical properties as recovered items (Halliwell, 3006}. It may also be difficult and

costly to retrieve discarded materials, clean them and re-use them. For example, the

reclamation of clay bricks: demolished bricks contain mortar and plasterboard, which must

be carefully dislodged, using labour-intensive methods (CIRIA, 200D). Furthermore, waste

materials cannot be re-used if their fire- resistant properties are unknown (Halliwell, 2006).


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Testing performance of waste materials

British/industrial standards are always used when examining the performance of

construction materials. The list of standards is comprehensive, and addresses a wide variety

of characteristics. Appropriate standards should be referenced for a selected waste

material. Some examples of the criteria used are listed in Table 6:

Table 6: Examples of British standards tor testing materials (UKAS, 2005)

Category Characteristics Examples

Appearance Colour, fluorescence, fracturing Efflorescence of clay bricks

(BS 3921)

Physical Strength, durability, density, flexibility,

particle size and shape

Compressive strength of concrete

(BS EN 12390: 2002)

Chemical Toxicity, stability, corrosion, moisture

content, flammability

Acid resistance of paving blocks

(BS EN 1344: 2002)

Further examples in regard to performance aspects of two construction waste materials

(waste wood and glass) are given below:

Performance of wood-chip mulch from recycled timber

Timber frame cut-offs arid waste wood may be used in wood-chip-mulch, which in turn is

widely used as a weed-suppressing surface layer in horticulture. Performance aspects

relevant to this application include (WRAP, 2006B):

durability (recycled timber-based mulches can last 2 - 5 times longer than natural bark

mulches due to a lower moisture content);

maintenance/replacement (better durability reduces the need to replace the mulch);

appearance (e.g. mulch sold to individual customers), and;

safety (treated wood might contain potentially hazardous pesticides or coatings such as

CCA).

Performance of recycled glass cullet

The performance requirements affecting the recycling of glass can be very stringent.

Although glass bottle recycling is widely conducted, even the trace presence of impurities in

the waste glass stream can damage the recycling equipment (e.g. furnace} or contaminate

the emerging product (Poulsen, 2003).

Another performance issue restricts the use of glass cullet in concrete. Research has been

conducted into the problem of alkali-silica reaction in concrete containing recycled cullet,whereby reactions between the glass panicles and cement can cause the concrete lo bulge


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and fragment (Dhir et al, 2003).

Having recycled or reclaimed products certified and tested may incur prohibitive costs;

Halliwell (2006) quoted a re-certification testing charge of approximately 1500 for a

trussed ratter, whereas original manufacture costs approximately 30.


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3: WASTE CHARACTERISATION TECHNOLOGIES

3.1: Introduction

A waste characterisation study often addresses a complicated mixture of materials and

contaminants being produced from several sources, at varying rates. Within this situation,

companies and organisations involved in waste re-utilisation may use advanced techniques,

including computer models and databases, in order to study the nature, flow and impacts of

waste streams.

Materials are also assessed using laboralory analysis according to accredited methods. Data

generated from the use of tools and equipment for a project must (Eikelboom et al, 2000):

provide adequate information;include limit of detection results which do not approach a specified limit (e.g. maximum

permitted concentration of contaminants),

provide unambiguous test results; and,

possess good repeatability and reproducibility.

3.2: Databases

The purpose of a database is to organise and assemble all relevant waste stream

information, thus making it more accessible and easier to analyse. This method isparticularly useful for organising the collection and presentation of extensive, highly

variable reams of raw data. Databases are also being developed to inform companies on

possible recycling options, and suppliers are registering their details through online

databases A few examples are briefly discussed in this section.

National databases in the UK

When selecting a material tor recycling, it is necessary to find out which companies in the

local vicinity might process the waste. If a company intends to market a reprocessed waste

material, it can now register its details online. Online data-bases of available recycledconstruction materials and suppliers on the British market have been produced by a number

of government agencies, in order to assist building contractors in maximising the use of

recycled products. A few examples are listed in Table 7 over-page.


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Table 7: Construction waste material databases in the UK (sources listed)

Mixed waste stream components

Several waste characterisation studies published in the field will contain extensive tables

listing a wide range of specific waste materials. A waste management database can hold the

following information (Bahu et al, 1997):

a general description of the waste and the source company; flows and quantities;

chemical composition;

storage area and description;

movements in and out of site, and a note of haulage containers used;

any associated hazards; and,

details of consignments leaving the site and their destination,

One recent example was a detailed study into the different wastes within construction and

demolition waste generated throughout California (Cascadia Consulting Group, 2006). In this

study, a computer database covering a wide list of waste materials was created, and datawere collected through surveys and sampling of wastes produced in sites within five


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selected urban districts. Using the database, estimations of the quantities and flows of each

waste material were recorded at each of the five sites, and statistical calculations were then

performed in order to estimate the waste flows throughout the state of California as a

whole. Records of all participating contractors were kept, each containing the raw data

produced at their sites.

Assessment of waste performance and potential risk

Databases may also be used when collecting and analysing an extensive range of

environmental data, which is continuously being updated. Such a database may be used lo

consider waste materials being recycled or used in different possible scenarios - thus the

potential environmental or hearth risks can be assessed.

An example may be a database of materials that contain information on the leaching of

potentially toxic metals. A flowchart lor creating and using such a database was proposed by

Van der Sloot et al(2003), as shown in Figure 5:

Figure 5: flowchart of methodology in creating a database on testing of materials (Van der Sloot et al, 2003}

Life Cycle Analysis is a method of assessing and measuring the told environmental impacts

(including toxic wastes, effluent discharge, greenhouse gas emissions, etc. of a material,

from "cradle to grave' (i.e. from the extraction of raw materials, to the final disposal of

wastes to landfill. Halliwell (2006) described three online databases, which are listed in

Table 8 over-page:


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Table 8: Life-cycle analysis databases (Halliwell, 2006)

3.3: Modelling

Construction waste generation is dynamic, as is its re-use or final disposal. Although

computer databases can process extensive reams of data and can be updated, the data

contained is static, and it may therefore be difficult to predict future waste stream

scenarios. Causes and streams of waste are inter-related and often interconnected. The

transfer of money in relation to waste management (taxes, purchases, etc.) is equally

complicated (Ehanayahe and Ofori, 2004). Researchers have developed computer models,

which emulate such processes. Three examples are discussed:

Economic impact modelling

If a construction sector-based company decides to recycle its waste or send it to a recycling

contractor other businesses linked with the materials and the operation will also profit as

well (Goldman and Ogishi, 2001). A study into the economic impacts and benefits of waste

recycling (and disposal) in a sector may address this complex network of purchases and

spending. Money is transferred from one business to another whenever a waste is disposed,

or recycled and sold, or when recycling equipment is purchased or maintained. If a company

is selling or recycling a waste, it may interact with several other businesses, which interact

with more businesses in turn (Goldman and Ogishi, 2001).

Goldman and Ogashi (2001) described a computer model, which simulated the flow of

waste materials and money throughout California. They predicted that if waste (including

municipal and commercial wastes) could be recycled, the total sales from materials within

the system could double, and employment would increase significantly. Likewise, if a

construction materials manufacturer could reprocess and sell a recycled waste at a profit,

then further investment into recycling could in turn generate further profits.

Predictinq the viability of aggregate re-processing

Another economic factor-based computer modal was described by Duran et al (2006), basedon the transfer of C&DW between construction site contractors and recycling firms. Based


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on results from questionnaires, the authors entered financial data for the activities of

recycling centres. Financial data environmental taxes, environmental incentives, and costs

relating to the distances between the construction silo and the recycling centre, were also

included in the model.

As is the case with any computer model, Duran et al (2006) also specified simplifications

{and thus defined the limits) in their model:

the construction site contractor always aims to maximise profits;

the construction site contractor either chooses a landfill site or the recycling contractor

nearby;

the aggregates used in the model are not replaced by other materials;

no illegal dumping occurs; and,

the recycling contractor only charges enough money to cover costs.

Inevitably, a computer model cannot predict every possible future scenario - only a probableoutcome, as baaed on a list of assumptions,

Predicting waste generation and potential recycling options

Chandrakanthi et al (2002) described a Canadian computer model, which was used for

integrated solid waste planning and analysis. The model was used to predict quantities of

waste being generated from a specific building project; quantify re-usable waste fractions;

optimise methods for storing and reprocessing the emerging waste; and identify costs of

different possible operations.

Figure 6 summarises the outputs of their computer model. This was produced by analysing

all the different activities on-site, using this information to predict the quantity of waste

being produced, and collecting background data on the costs involved in transporting (on-

site to recycling bins) and reprocessing/landfilling of the waste.

Figure 6: A simulation model of waste production and management at a construction site, activities included in

cost analysis (Chadrakanthi et al, 2002)


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3.4: Assessment

The suitability (i.e. performance, safety) of waste materials can be assessed using British

standards and other industrial testing criteria. If the characteristics of the waste material

satisfy such requirements, an assessment of the economic viability of possible recycling

projects is also performed, as previously described in Section 2.7.

Assessing the suitability of recycling: general considerations

When assessing a waste material or the recycling technology required, the following

questions should be addressed (CIRIA, 2000):

Is the market value of the material comparable with that of the equivalent primary

material?

Is the market value of the material suitable to match the costs of having it recycled?

Is the material available in sufficient quantities and at appropriate times?

Is the material durable?

How pure and how safe is the material?

What extra maintenance or additional components are required if recycling the material

(e.g. adding it to the raw material within a manufacturing plant)?

Will using the waste material on-site create additional costs (e.g. increased preparation

time)?

Is a proposed method of recycling the material the most efficient?

Although a wide range of potential recycling options may be recommended for construction

or demolition waste materials, in practise, waste recycling may be restricted to a fewfractions or materials, A selected waste material needs to be assessed in terms of its

potential market value, compatibility with other materials (or machinery), and its

composition (Tam and Tam, 2006).

Waste materials regulations

It is necessary to ensure that the re-use of a waste material is permissible under

environmental legislation, and does not present a significant health or environmental

hazard. Although construction products themselves do not pose a risk whilst in use,

individual materials or wastes generated from the construction industry or demolition maybe intermingled with potentially hazardous or damaging residues (USEPA, 2004). Waste

materials may generally be classified as hazardous (i.e. must be disposed of), contaminated,

or fit for purpose. At present, all Industrial waste (including construction and demolition

waste) is classified as Special Waste (nowadays defined as "Directive' waste), and requires

examination (Figure 7 and Table 9 over-page).


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Figure 7: methodology used for classifying materials (as required in the EU) (Environment Agency, 2006)

Table 9: materials and properties addressed under the Hazardous Waste Regulations 2005 (Environment

Agency, 2006)

Materials included in The List - construction and demolition wastes (including soil)- wastes from wood processing- wastes from production ofpanels (e.g. frames)-

wastes from shaping/cutting of plastics and metals

Hazardous properties

(summarised)

- flammable, explosive- carcinogenic, toxic, mutagenic- irritant, harmful to health

The classification of construction waste materials as being either hazardous or non-

hazardous is often a matter of judgement, particularly since a waste stream (namely

plastics) may contain a range of different materials. Certain materials such as lead piping

and asbestos can readily be classified as being hazardous. Assessing the possible

contamination of waste materials (from chemicals such as toluene, or mercury from

fluorescent bulbs) can be more onerous (USEPA, 2004). A wide range of analytical

instruments such as X-ray fluorescence (XRF), gas-chromatography-mass-spectrometry

(GCMS) and flame emission spectrometry may be required for testing materials.


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4: METHODOLOGIES

A waste characterisation research methodology is a logical guideline used to assist those

involved in a project. A methodology emphasises that important aspects which need to beconsidered, rather than outlining a sequence of tasks (John and Zordan, 2000).

Three prime issues associated with waste characterisation are addressed in this chapter:

-the quality of the data produced, which depends on how the waste stream is sampled;-quality and appropriate use of analytical tools (including computers and lab Instruments),

which strongly determines the usefulness of data produced; and,

-the development of an effective marketing strategy, which aims at attractingcustomers/purchasers and generating profit.

4.1: Sampling Strategy

Detailed surveys of waste streams and their processing stages are time- consuming and

difficult to conduct, and results will therefore carry a significant margin of error (Gay et al,

1997). The analyst cannot collect or analyse all the material from a waste stream, and the

source company may not accurately quantify its waste streams either. Representative

sampling of materials therefore needs to be conducted (Bahu et al, 1997), and estimations

need to be made on total waste quantities, flow rates and composition.

Sampling strategy and record-keeping

A sampling procedure includes initial planning, identifying suitable waste streams,

completing the field documentation, collecting samples, and/or having samples packaged

and stored prior to analysis (Popek, 2003). Physical samples should be identified with

unique sample numbers; they must be efficiently tracked, and should not be cross-

contaminated by different samples. Records should include (sample collection) time,

location, contact details (e.g. company, site manager), and the type of sample (collected or

discussed) (Popek, 2003).

Sampling errors

The sources of error from the sampling procedure include (Popek, 2003):

- errors due to the variability of the waste stream (composition, rate of production, etc);

- errors due to the population variability (i.e. is the sample from one source similar to those

from other sources?);

- sampling design error; and,

- errors in sample collection and storage.


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The first two types of error are quantitative; both can therefore be controlled using an

appropriate random sampling strategy, and statistical methods can be used to assess the

margins of error. The third and fourth sources of error are qualitative, and may be harder to

measure. Sampling design errors can arise if available information on the waste is limited

and if some sources of waste are not identified (Popek, 2003). A researcher should consider

the varying rates and sources of waste production. He/she should define how often or how

much of a waste strewn should be sampled, define a sample size, and decide how many

replicates of a sample are collected (Gay et al, 1993).

Nevertheless, sample collection is limited by time, coat and the mass of the collected

samples themselves. Several waste characterisation studies recommended that waste

samples weighing between 90kg and 180kg should be collected from a mixed waste stream;

this would require special collection and transport of samples. Multiple sampling of the

same waste streams over many weeks and months is often too expensive and time-

consuming for most projects (Yu and MacLaren, 1995).

Researchers involved in waste characterisation use representative sampling (Bahu et al,

1997), whereby a restricted number of sites are selected at random, and collected data is

used to represent the entire waste stream (Govt of Canada, 2005).

Cascadia Consulting Group Inc (2003) reported on a survey of landfill waste, whereby equal

numbers of samples were collected during summer and winter months; during each period,

the timing and order of visits to sites was randomly planned. At each site, 14 replicates were

collected, and information on the numbers and types of haulage vehicles was also obtained,

in order to predict flows and quantities of waste- Random samples were collected, whereby

waste in a ripping area was poured into 16 disposal banks, and site personnel chose twobatches at random. Average waste composition was estimated using variance and

confidence intervals.

Whole waste stream and individual materials

It is important to consider both the sampling of individual materials, and wrote waste

streams (Bahu et al, 1997). If a whole waste stream can be recycled, a recycling company

will encounter tower capital costs from purchasing processing equipment. On the other

hand, some individual materials in a waste stream may carry a high market value, and are

therefore worth isolating.

4.1: mixing of samples

A mixture of wastes (especially demolition waste) will vary greatly in particle size,

particle/object shape, and density. If studying such a complex waste stream, good mixing of

the waste prior to obtaining samples should be performed, especially if the purpose of the

project is to select appropriate waste segregation equipment (e.g. screens) (Bahu et al,

1997).


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Sample data from surveys

Yu and MacLaren (1995) compared the use of Direct Waste Analysis (DWA, e.g. field visits

and sample collection) with surveys, in order to estimate waste production. The use of

surveys can incur considerably lower costs, when compared with sample collection and

laboratory analysis; respondents will also understand the nature of the waste stream, such

as seasonal variation in the rate of production. Nevertheless, the method has its limitations:

most respondents will not answer long, detailed questionnaires this reduces the

quantity (and reliability) of the overall data gathered;

respondents may often discuss quantities In terms of volume; converting such data into

mass flows does not take the density of the materials into account; and,

respondents often make rough estimates.

4.2: Analytical methodology

Once samples are collected, at least a few preparation steps may be taken before test

results can be generated. The reliability of results depends on how carefully a sample is

stored, processed into an analyzable form. And analysed (i.e. how reliable the analytical

instrument is). The results generated may be used as raw data. or may require one or more

calculations in order to express results using specific units. Waste material testing and

analysis must produce results which are accurate, and which do not reflect contamination of

the sample, or interferences affecting the data output (Manahan, 2001).

The storage, preparation and analysts of samples must meet required standards; wheneverpossible, and an accredited laboratory facility should be used. Replicates (at least

duplicates) of samples should be processed and analysed using precisely the same method,

ideally at the same time. Data alongside sample results should include (US Dept of Energy,

1996):

detection limit studies (and statistical methods of determining this);

studies into the predicton and bias of results;

blank results to check for contamination in equipment and reagents; and,

proof that no cross-contamination has occurred.

Two examples of lasting methods and their analytical standards are discussed below:

Testing hardened concrete (BS EN 12390)

The compressive strength of concrete has been tested for many years using concrete cores,

by crushing them using a core compressor, illustrated in Figure 8 over-page. BS EN 12390

(2004) provides a comprehensive list of instructions which address:

the shape, dimensions and other requirements of specimens:

producing and curing specimens; and,


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assessing the compressive strength, and calibrating the compressive strength testing

equipment.

Figure 8: a concrete core compressor machine (Qualitest, 2006)

Examples of requirements listed in BS EN 12390 include the following:

specimens must be tested for compressive strength al 20C (10 C):

specimens must be tested using a strain-gauged column which is 100mm diameter and

200mm high; specimen cubes must be characterised by a completely horizontal surface at both ends,

and must stand perfectly straight; and,

the force Indicator on the machine must produce results with an accuracy error of less

than 3% (maximum).

Leaching of trace metals from waste materials

A revised standard addressing leaching tests from solid waste material samples (or

construction materials containing wastes) was recently published by the Environmental

Agency (2004). The NEN7375 leaching lest involves preparing a sample cube (e.g. concretecontaining recycled aggregate), and immersing this in water over a period of 64 days (Figure

9, over-page as per the usual). Trace metals teach into the surrounding water, and leachates

are collected at set intervals during the experiment. Analytical requirements for the

experiment include:

specifications ofsample size and dimensions (cube, >4cm);

use of distilled water to minimise contamination;

replacing the water and collecting water samples at specific intervals;

pH measurements of the water (whereby the pH meter must possess an accuracy of 0.05

units); and,


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checking that none of the equipment used releases trace metals into the water or sample

(or absorbs metals).

Figure 9: the NEN7375 leaching test in operation (Van der Sloot, 2005). Concrete cubes are immersed inside

water tanks (towards the left).

4.3: Marketing

Marketing is often perceived to be the advertising, promoting or sealing a new product or

service. However, this interaction with potential customers comprises only the final stage of

a long and carefully co-ordinated strategy. The whole marketing process begins with acompany manager (or management team) deciding what they are going to produce and sell,

and assessing whether or not their organisation is capable of meeting the challenge.

Marketing activities

Marketing activities are needed to assess the level of organisational competition and the

level of customer demand. These require time, financial and resources investment in the

marketing process, in addition to anticipation of early setbacks line product may not sell

quickly at firsts and marketing methods may have to be improved. Most importantly, there

is a need to assess the price tag on recycled wastes if compared with materials readily

available in the market. Indeed, if a recycled material is not significantly cheaper or higher

quality than the equivalent conventional material, it may not a successful marketable

product (WRAP, 2006).

The volatility of the market, and the attitudes of customers should be Investigated through

background research and possibly by conducting surveys (e.g. questionnaires with potential

buyers). An internal audit of the company's resources, staff skills and budget should then be

conducted, in order to predict whether or not the business is capable of entering the

market, and what resources (e.g. machinery, recruiting specialist staff) are needed (WRAP,

2006).


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Once these studies prove lhat the company is capable of producing a marketable product,

an adequate budget must be assigned for promoting, designing and producing the product.

Thereafter, the process of advertising, networking and demonstrating the product can be

undertaken (WRAP, 2006),

It has been reported that several potentially successful recycling technologies and their

emerging products may not become profitable. Environmental and technical excellence

alone may not lead onto creating a new market. Successful marketing and its resulting

profits depends on market's confidence, networking between recyclers and client

companies and consumers. Communication with government agencies, research institutions

and community groups can also be beneficial. All interested parties should collaborate in

developing, evaluating and enhancing a recycling process (John and Zordan, 2000).

The Break-Even Point

In order for a company to predict the profitability of reprocessing a waste material, theBreak-Even Point needs to be estimated. As soon as the operation commences, the

company might initially be incurring a loss, since sales will be modest at first, before

increasing over lime. Reprocessing costs occur in two categories: variable costs (i.e. the

more sales, the more labour and energy consumption required); and fixed costs (rent,

business tax, depreciation of equipment). Over time, the profits generated should exceed

the sum of both types of cost, as shown in Figure 10 (Stenis, 2004; WRAP, 2006):

Figure 10: progression of sales towards the Break-even Point (Stenis, 2000)

Promotion of recycled products by WRAP

The Waste & Resources Action Programme (WRAP) is directly involved in developing new

markets for recycled products in the UK. Its objectives include: (i) creating confidence in

markets; (ii) investing in waste recycling and marketing projects; and (iii) ensuring that

waste materials are adequately sorted, collected and recycled. The organisation has funded

a range of projects and worked with local councils; two examples are listed in Table 10

(over-page).

Time

Profits

Variable costs

Fixed costs

Break-even point


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Table 10: Examples of marketing activities undertaken by WRAP (2005)

Marketing and product design of recycled plastics

When developing and marketing a recycled product, it is necessary to:

acquire background knowledge on types and uses of a product;

compare benefits of the new product with established products;

conduct a market survey, in order to assess peoples' interest; establish a price (which will

attract customers); and evaluate the size of the market;

evaluate and characterise the waste material feedstock;

get quotations on the recycling equipment needed; and,

examine all costs involved in recycling (Pringle and Barker, 2004).

Using all the above data, a product can tie successfully marketed, given that survey andcharacterisation results are favourable. Pringle and Barker (2004) described a marketing

method of promoting the recycling of shredded HDPE, in order to produce and sell plastic

fencing posts for agricultural use. The main stages are summarised in Figure 11:

Figure 11: Methodology for marketing recycled plastic fencing (Pringle and Barker, 2004)


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5: CONCLUSIONS AND FURTHER WORK

5.1: Summary of findings in the literature review

This report discussed the approaches, technologies and methodologies of waste

characterisation. Waste characterisation approaches address the type of information which

is required. Waste streams and materials must be quantified, classified, and analysed tor

their physical and chemical composition. Their performance characteristics must also be

studied, along with the economic factors affecting their potential for being recycled and sold

on the market.

Waste characterisation studies are dependent on technological tools, including computer

databases, computer models, and laboratory instruments. Databases can be used to

assemble extensive information on waste streams and details such as composition; they canalso be used to list and promote companies selling recycled construction materials;

Computer models enable researchers to predict future scenarios (e.g. the economic changes

if more recycling is conducted), or to map waste stream movements. Laboratory

instruments can be used to assess waste materials: one example is the analysis of

"dangerous substances' classified in the EU as hazardous.

Three methodologies of waste characterisation were also addressed. These strategies were

sampling, analytical techniques and marketing. Sampling of waste materials must be

carefully designed, since only a few representative samples from a large waste stream may

be collected. Data may also be collected through surveys which are more cost-effective, but

which may yield limited data (as potential interviewees may not be interested in

participating). Analytical techniques include sample preparation and analysis in the

laboratory. Sample contamination, the accuracy of data output from the instruments, and

the precision and accuracy of data generated, need to be considered. A marketing strategy

is also important, in order to bring a new recycled product to the attention of customers,

contractors and other clients.

Further work

Within the context of the Be-AWARE project, information regarding waste quantities, costs,

their present recycling status and/or recycling potential has been collected through waste

mapping interviews, and the first Be-Aware workshop.

The next stage involves data collection in regard to the performance and economic aspects

of waste materials So far, only nine waste mapping data sets of construction product

manufacturers have been produced, hence more waste mapping information will be

captured through interviews across four sectors: plastic; timber and wood; cement and

concrete; and bricks and blocks.

Issues regarding the economic and performance aspects of waste materials, that need to be

addressed during the next Be Aware project stage include:


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the existing and potential markets for recycled products in the UK;

the technologies used to reprocess or re-use waste materials;

performance-based factors affecting the recycling and sale of reprocessed products:

o contamination, hazards, impurities;

o degraded properties (e.g. strength, appearance);

o working lifetime of products;

o incompatible materials, limited technology;

o ease of segregating/retrieving material for recycling or reuse;

economic factors affecting the reprocessing and sale of materials:

o existing market opportunities for recovered materials;

o viability of acquiring and using certain recycling processes;

o regulation and classification of materials as wastes - and costs of having a recycled

product accredited as fit-for-purpose; and,o the limits to distance of transporting materials.

These issues will be addressed through a waste characterisation survey and facilitated

activities of the second Be Aware workshop (Workshop 2: Performance and Economic

Assessment which was held on 5th

February 2007).


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REFERENCES

Note: websites are no longer accessible


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waste characterisation literature review

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