Article - Issue 20, August/September 2004

Wasting future resources

Hywel Thomas and Jim Poole

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Humankind places great demands on the Earth’s life support systems that can no longer be sustained. As a result, we are facing a range of environmental problems, including loss of bio-diversity, resource depletion and global warming. Changing the way in which people behave in ways that are acceptable to society is an enormous challenge, especially in relation to how waste is managed affordably. Sustainable development provides the appropriate context for considering waste as a resource and improving our way of life.

What makes something waste as opposed to being simply another material? At first it seems strange that iron ore should be considered a valuable resource, while a used steel can is branded as waste (even though it is a lot closer to being a desired product, such as another steel can or part of a car).

Whether a material is defined as ‘waste’ depends on whether or not there is a guaranteed use for it, and not on any assessment of its inherent physical properties. Classifying a material as waste may prejudice its use by industry as a resource. Any such waste has to be handled within the formal waste management framework until it is put back into productive use. This clearly has implications for any strategy that seeks to treat waste and raw materials even-handedly.

The more detailed European Directives are, however, the driving force for a whole range of improvements in waste management in terms of stimulating recycling and the efficient use of resources (see Box 1).

Box 1 - Principal EC Directives in the field of waste management from the perspective of resource recovery

The Landfill Directive requires:

  • the treatment of all wastes prior to landfill

  • by 2010, 2013 and 2020 no more than 75, 50, and 35 per cent respectively of the biodegradable municipal waste produced in 1995 to be landfilled

  • the cessation of co-disposal of hazardous and non-hazardous waste after 16 July 2004

  • banning the burial of whole tyres in landfill as from July 2003, and of shredded tyres from July 2006

The End of Life Vehicles (ELV) Directive requires:

  • by January 2006 and January 2015 (for all ELV) that re-use and recovery shall be increased to a minimum of 85 and 95 per cent respectively by an average weight per vehicle and year

The Packaging and Packaging Waste Directive:

  • sets minimum targets of 50 per cent recovery and 25 per cent recycling for relevant materials by 2001, rising to 60 per cent recovery and 55 per cent recycling by 2008. Relevant materials include paper, board, timber, glass, metals, plastics, ceramics and the like. Specific targets are set for each material by 2008.

The Waste Electrical and Electronic Equipment (WEEE) Directive requires:

  • setting targets and deadlines from 2005 in terms of collection systems, and 2006 for rates of separation, recovery and recycling

The waste hierarchy

Every year, the quantity of waste produced in the UK has been increasing. For example, over the past four years the production of domestic and municipal waste has increased by around 3 per cent annually. This should not, however, be seen as inevitable. The concept of a ‘waste hierarchy’ has been devised as a way of reducing the amount of waste produced as efficiently as possible, and with least environmental impact (see Box 2). Under this hierarchy, preventing waste production in the first place is the most favoured option and disposal to landfill or by incineration the least favoured. Of course, there may be overriding reasons for incineration such as the destruction of toxic waste.

This thinking is reflected in the European Union’s 6th Environment Action Programme and in two recent communications from the Commission, proposing thematic strategies on the Sustainable Use of Natural Resources and on the Prevention and Recycling of Waste. In a similar vein the UK Government launched, in September 2003, a ten-year framework for sustainable consumption and production. In doing so, the Department for Trade and Industry emphasised that inefficient use of resources costs UK industry £3 billion a year.

The Wales Waste Strategy

The four home countries of the UK have prepared separate strategies outlining how they intend to meet their share of the UK’s waste targets. The National Assembly for Wales has set local authorities targets for increasing recycling and composting by 15 per cent by 2003/04; 25 per cent by 2006/07; and 40 per cent by 2009/10.

Currently Wales recycles only 7 per cent of municipal waste. The change in behaviour that would be required to achieve a 40 per cent recycling/composting target is summarised in Box 3. These figures illustrate the challenges faced in persuading people to participate effectively, and in designing procedures that they find easy to use.

Health and public perception issues

Waste handling facilities are frequently unpopular with local people. Even when adverse impact on health cannot be demonstrated, public nuisance is often cited as the basis for compensation claims. This is particularly the case for landfills and waste incinerators. In this context, it is interesting to consider the various treatment and disposal routes for used tyres (see Box 4).

It’s easy to see how anxiety about safety could dissuade people from using remoulds, and concern over the health impact of emissions could make use of tyres as a fuel unpopular. In this climate, it is not sufficient simply to produce evidence that is credible within the scientific and engineering community – the public must also be persuaded.

Box 2 - The waste hierarchy

Prevent waste production by developing clean production technologies and designing products that have little environmental impact over their entire lifecycle.

Minimise waste production and hazardousness by ensuring efficient use of resources within existing systems and phasing out the use of hazardous materials, such as toxic metals.

Re-use by re-using raw materials and packaging and by refurbishing other items, ranging from clothing to railway trains.

Recover materials by reintroducing materials to the economic cycle (e.g. recycling of glass or paper) or returning materials to the environment in a useful and harmless form (e.g. using compost as a fertiliser).

Recover energy either after treatment by combustion, mechanical or biological means to produce a fuel for energy recovery (e.g. gasification, anaerobic digestion) or use as a fuel directly.

Dispose through burning (without energy recovery) or landfill.

Box 3 - System required to achieve 40 per cent recycling of household waste, assuming that 67 per cent is the most that could be sensibly recycled

  • 100 per cent provision of kerbside collection and bring sites.

  • 80 per cent of households will need to use the recycling service.

  • These households must segregate and put out at least 80 per cent of the recyclable wastes.

  • The contamination/rejection rate of this segregated material must be less than 5 per cent.

Box 4 - Alternative routes for the treatment and disposal of used tyres

Retreading – suitable for around 15 per cent of used tyres, this involves replacing the old tread with a new one. Re-use – either for use on other vehicles (provided sufficient tread) or for use in landfill engineering, dock fenders, artificial reefs and playground swings. Material recovery – grinding to produce a rubber crumb that can be used for surfacing sports halls, playgrounds and roads, carpet underlay, street furniture and acoustic barriers, as well as incorporation into new tyres. Energy recovery – used as an alternative fuel to coal.

The role of engineering in the solution of these problems

The Engineering challenges that arise as a result of the current situation are considerable. This is obviously both a problem and an opportunity for the community. It is, however, indisputable that these challenges must be met and set within a wider social context to ensure a sustainable future for all.

Clearly Engineers have played a significant role to date. Examples of importance include the development of effective incineration plants, advances in composting technologies and improvements in the containment techniques adopted in relation to landfill sites.

Ongoing research and development is necessary to achieve further advances, particularly in relation to waste as a resource. To illustrate these points, three projects, currently being conducted locally in Wales will be discussed. It is acknowledged that a significant research effort worldwide is now being developed in this regard and the work discussed should therefore be viewed in this context.

The three projects, each with a geoenvironmental dimension are:

  • the development and operation of a new full-scale composting plant

  • the creation of a geoenvironmental research park

  • the operation of a Land Regeneration, Industrial Waste and Sustainable Development Network

The development and operation of a new full-scale composting plant

If one accepts that the recycling/ composting targets outlined in Box 3 will be achieved, it obviously follows that the volume of material to be composted will increase dramatically (240,000 tpa by 2010). To respond to the challenge that will thus be created, a number of initiatives have been launched, aimed at providing the technology and infrastructure required for the composting of segregated organic waste. The composting plant described below is one such initiative, focusing on the technological aspects.

The technological challenges being addressed are those of an improved understanding of (i) the processes taking place during composting of green waste (at full scale); (ii) the quality of the compost being formed; and (iii) the developments necessary to ensure the composting of mixtures of municipal solid wastes and food waste (covered by the Animal By-Products Regulations). In relation to the quality of the compost, current indications suggest, for example, that plants germinate just as easily in this type of compost as when planted in current composts on the market. However, trials also indicate that plant growth is not as vigorous in this new material, and this aspect, for example, will need to be addressed.

This new facility is operated by the Cardiff School of Engineering (Centre for Research in Energy and Waste) in conjunction with the Carmarthenshire Environmental Resources Trust. The plant currently handles just less than 20 per cent (about 4000 tpa) of the present composting capacity. It was commissioned in 2001 with the research phase scheduled to last for five years.

Site facilities

The site is located at Carmarthen’s Environmental waste management centre, some six miles east of the town. It comprises a 1500 m2 covered area with a closed drainage system and 1700 m2 of external concrete paved area (see Figure 1).

Equipment

Basic equipment consists of a SEKO 600/200 shredder (see Figure 2), a SP400 Menart windrow turner (see Figure 3) and a Menart 4-metre trommel with 400 mm and 100 mm screens (see Figure 4).

The site is operated under a waste licence from the Environment Agency and is one of only six facilities in the UK to be awarded the status of ‘best practice site’ by the Waste and Resources Action Programme (WRAP). It is currently in the final stages of gaining accreditation by the Composting Association under its PAS100 scheme.

Research to date has centred on developing tools to optimise the windrow composting process. This technique has been used to establish:

  • when the compost has become stable and does not require further processing before storage or application to soil

  • the effectiveness of the turning regime

  • the need for adding a source of Nitrogen (poultry farming waste has been used)

Research over the last year has also been directed towards equipping the site to handle waste covered by the Animal By-Products Regulations. This work has been conducted in conjunction with the State Veterinary Service in Carmarthen. This has seen the operation of a commercial invessel, containerised composter of 40m3 capacity. Also studies using forced-air circulation in a bay of 100m3 capacity using mixtures of Municipal Solid Waste and food wastes as feeds have been carried out. This work has led to the design of a plant capable of being retrofitted to the existing plant, thus providing the ability to handle 10,000 tonnes of catering waste per annum

A geoenvironmental research park

To address a wider range of waste materials and streams, the Cardiff School of Engineering, through the activities of its geoenvironmental research centre, recently established a geoenvironmental research park.

The overall objective of the project is the pursuit of, research, development and technology transfer in the area of waste minimisation and re-use. The wastes being considered are typically those arising from industrial and construction/demolition processes. Given the growth also foreseen in waste arising from these sources, coupled with the need to direct such waste streams from landfills, re-use of such materials as a resource in new endeavours can clearly be seen to be of potential importance. The overall aim of the project can therefore be seen as a contribution towards the development of a sustainable geoenvironment.

To achieve these aims the Research Centre leads a consortium of partners, namely the Welsh Development Agency, BP Chemicals Ltd, TRL Ltd, Aggregate Industries, Minton Treharne and Davies, Hafren Group, and Excel Industries Ltd.

To illustrate the type of work being performed, one project ‘Vegetation growth trials on alternative materials’ will be described. This project, which is being led by TRL Limited, addresses the amount of construction and demolition waste, and the amount of basic oxygen steel slag being generated in the UK. For example, the annual amount of construction and demolition waste produced in the UK is currently estimated at 85 million tonnes (17 per cent of UK waste production). Basic Oxygen Steel Slag is also produced in large volumes and generally stockpiled. One solution to utilising these materials is as engineering fill, thus reducing the waste requiring disposal and the impact of using sub-soil.

Trials are under way at the research park to test the performance of a 90- metre-long, 2-metre-high flood protection bund, constructed in three sections, each with a different core material: construction and demolition waste, basic oxygen steel slag and a locally sourced sub-soil. Each section of the bund has been seeded with grass and planted with shrubs and trees to assess the ability of the two alternative materials to sustain vegetation in comparison to the sub-soil control (see Figure 5).

It is anticipated that the outcome of the trials will be the development of guidelines for the selection of suitable vegetation species in landscaping and engineering applications for waste and alternative materials. Whilst only sixteen months into the monitoring programme, the indications so far are positive in terms of applications for sustainable construction and landscaping.

A second overall aim of the project is to enhance economic activity in selected areas of Wales via the development of new Environmental Technology concepts/ideas, which can lead to new business for existing companies, or the creation of new companies. In terms of this aim the project has to date yielded the results shown in Box 5. The research park is on track to exceed its project targets.

Further development of this whole initiative is now taking place. In particular the research park’s future activities will be linked to support a new Sustainable Technologies Technium* currently under construction in West Wales. In this way it is hoped that further benefits can be gained for the economic well-being of the region.

The operation of a land regeneration, industrial waste and sustainable development network

The final example presented, also developed by the Cardiff School of Engineering via the activities of its geoenvironmental research centre, is that of a Land Regeneration, Industrial Waste and Sustainable Development network. The importance of the ‘waste hierarchy’ has already been discussed in this article. As stated, it is generally accepted that effective management of future resources, including waste, is closely linked to the implementation of these ideas.

Mechanisms that can assist in the process of implementation are therefore both desirable and welcome and form an important part of the delivery of the strategy.

The importance of the Land Regeneration, Industrial Waste and Sustainable Development Network is that it has established itself as a useful and effective component of this delivery mechanism, all against a background of a rapidly evolving legislative/advisory framework. The objective here is, therefore, not the direct pursuit of research but the communication of information and good practice to the community as a whole. The network was established and held its first meeting in December 1999. To date the membership stands at over 1250 individual members from a core of approximately 890 local stakeholder organisations, approximately 730 of which are SMEs.

A major feature of the project is the inclusion of all stakeholders solving the problem in the network. This aspect is believed to be of central importance and the fundamental reason for the success it has enjoyed. This approach is in contrast to, for example, evening meetings organised by one sector and for that sector alone. The network provides opportunities for companies providing services in this area to meet and interact, not only as company/company contacts but also company/client discussions.

Greater links with other European and national networks and organisations are also facilitated, enabling flow of information on funds, regulations and news/events. Links with academia and research sectors are strengthened to encourage interactions between industry and research and to facilitate transfer of technology.

One of the main operating procedures of the network is that of informal evening meetings. These are held at locations across the whole of Wales, at venues both in South Wales and in North Wales. Topical and/or regional issues are included as considered appropriate. Information dissemination is also provided via http://www.grc.cf.ac.uk/, which is proving to be of major importance in the delivery of the Network’s work.

*A technium is a sector-specific business innovation centre geared to support companies with high growth potential and encourage innovation, research and development.

Acknowledgements

The authors would like to acknowledge (i) the contributions of colleagues in the Cardiff School of Engineering, namely Professor A J Griffiths and Dr K P Williams (Composting plant), Dr R W Francis (Research Park) and Dr D H Owen (Network); (ii) the various funding bodies associated with this work, including the Welsh Assembly Government; and (iii) numerous collaborators, including the Welsh Development Agency and Environment Agency (Wales).

Box 5 - Geoenvironmental research park performance targets (to date)

  • Companies created: 6

  • Companies assisted: 151

  • Jobs created: 20

  • Jobs safeguarded: 24

  • Patents registered: 2

  • Firms provided with advice on Innovation, R&TD: 219

  • Collaborative projects between firms and research institutions: 30

  • Projects transferring environmental technology to the business sector: 10

H R Thomas FREng

Head, Cardiff School of Engineering And Director, Geoenvironmental Research Centre, Cardiff School of Engineering

J Poole

The Royal Academy of Engineering Visiting Professor In Engineering Design For Sustainable Development, Cardiff School of Engineering

Hywel Thomas is Head of the Cardiff School of Engineering and Director of the geoenvironmental research centre within the School. He has been a member of staff at Cardiff University since 1980 having previously trained as a Chartered Civil Engineer with Scott, Wilson Consulting Engineers. He is a Fellow of the Institution of Civil Engineers and was elected a Fellow of the Royal Academy of Engineering in 2003.

Jim Poole has spent more than twenty-five years working with Welsh Water, the National Rivers Authority and now the Environment Agency. He is currently Sustainable Development Manager at Environment Agency Wales. In 2002 he was appointed as the Royal Academy of Engineering’s Visiting Professor in Engineering Design for Sustainable Development at Cardiff University.

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