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First published 2014.
Copyright © 2014 The Open University
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ISBN 978 1 1188 6393 0
1.1
In this text I have assumed that you do not have a background in wastes management, and that you are studying this material to gain an insight into the methods available to treat wastes and the environmental impacts of the treatment options.
In the past, waste management was almost exclusively concerned with disposing of wastes. In effect it was a logistics issue – what is the most effective way of collecting the waste, transporting it to a landfill site and depositing it in the site?
For many reasons, which I will discuss in this text, this is no longer the case and it is better to think in terms of ‘resource management’ rather than ‘waste management’. In other words, this text is asking the question:
How can we take products that one sector no longer needs and make them into useful resources for another sector?
With this question in mind, the text explores what waste is and the technologies for managing wastes, and considers the impact that waste and its management has on people’s health. It explores waste policy and practices in different countries, and finally looks at how different waste processes can be combined in the process of ‘integrated solid waste management’.
The self-assessment questions (SAQs) located throughout the text will help you to review and remember what you have read.
At first sight, this is a simple question, but it is one that we need to answer. A number of years ago I asked my children what waste was, and their answers were:
‘What we produce and throw away: things we don’t need’ (Andrew, aged 11)
‘Rubbish and stuff that people don’t want’ (Christopher, aged 8)
On a more formal basis, the Basel Convention (an international agreement on the exporting of hazardous waste) states that:
‘Wastes’ are substances or objects which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law.
(UNEP, 2011, p. 16)
Spend a few minutes thinking about this definition and write down your thoughts.
All sectors of the economy produce wastes and have their own terms to describe their wastes. Furthermore, different countries classify their wastes in different ways, and have different legal definitions of wastes in general and of the types and categories of wastes. This can be confusing, so to help you through it I have put together a summary of some of the more important terms in the box below.
Inert waste: Waste that poses virtually no environmental or health threat on disposal. Clean waste ceramic materials and uncontaminated soils would come under this category. Rocks and soils removed during mining and quarrying operations would also be classed as inert wastes (assuming that they ever left the site and entered the waste system).
Hazardous waste: Waste with the greatest potential for causing harm to the environment or public health (e.g. toxic substances, flammable liquids, asbestos, strong acids and alkalis, etc.). Many countries have a formal definition of hazardous waste. For example, the European Union’s List of Wastes (European Commission, 2000) states which wastes are to be classed as hazardous.
Household waste: The waste produced in domestic households and gardens. This is much more than the residual waste that we put out for disposal, because we may reuse a lot of the wastes we generate, dispose of them within the garden, etc. The contents of a kerbside recycling box or a recycling bank in a public car park are classed as ‘household waste’; so are the wastes taken to household waste recycling centres (HWRCs), and so is street litter.
Municipal waste: The definition of this varies from country to country, but it generally covers household waste (see above) plus waste with a similar composition generated by the commercial, government and educational sectors.
Clinical waste or healthcare waste: Waste generated by healthcare activities. The main sources are hospitals, GPs, dentists, vets, laboratories, etc. but healthcare waste can also be produced in the home (by people requiring daily injections, for example). The wastes in this category range from used sticking plasters through to drugs, human organs and body parts. Again, most developed countries have legislation defining and classifying healthcare waste.
Industrial waste: Waste produced by the manufacturing industry, which can cover everything from inert wastes to hazardous wastes. Industrial waste often has a greater potential for recycling than household waste because it is produced in a relatively small number of locations and has a known composition. Furthermore, the producer is directly responsible for its management and bears the cost.
Commercial waste: Waste produced by commercial businesses. This is similar to household waste but tends to contain more paper products. Note that there is a certain overlap between commercial and municipal waste.
Radioactive waste: Waste that undergoes radioactive decay. The military, civil nuclear power stations, hospitals and research laboratories are usually the main producers of radioactive waste. However, radioactive items (such as smoke alarms) are also added to the waste stream at home.
Biodegradable waste: Waste that can be broken down by microbial action (for example paper, card, food waste and garden waste). This is of particular concern because it is the biodegradable components of waste that give rise to landfill gas formation. Many countries (including all EU member states) limit or ban the landfilling of biodegradable wastes. Note that wastes (such as paper) that partially degrade are sometimes termed ‘semi-biodegradable’.
Note that many wastes fall into more than one category. For example, vegetable peelings are both household waste and biodegradable waste, and some types of healthcare waste would also be classified as hazardous.
The amount of each type of waste produced by a country will depend on its population and state of development. For example, Figure 1 and Figure 2 present the situation in India (population c.1 080 000 000 in the sample year) and England (population c.51 500 000 in the sample year) respectively.
Figure 1 Waste production in India, 2005 (million tonnes) (Pappu et al., 2007)
Figure 2 Waste production in England, 2008 (million tonnes) (Defra, 2011a)
Using Figures 1 and 2, comment on the differences between the two sets of data and suggest reasons for the differences.
The composition of a given waste stream is highly dependent on the process that gave rise to the waste. To take a couple of obvious examples, I would expect the waste from a quarrying operation to consist mainly of rubble and soil, whilst the waste produced by an administrative office complex might contain high proportions of paper.
For the remainder of this section I will be concentrating on household waste, and have adopted the following broad definition:
The waste produced in domestic dwellings as part of normal day-to-day living.
Note that, as stated previously, this covers much more than the waste deposited in dustbins. For example, it also includes:
Household waste is one of the more interesting waste streams because it contains everything that people have used and want to throw away. From the waste industry’s point of view it is also the most challenging category of waste to manage, because:
Many factors control the amount of waste a household produces and the composition of this waste. Make a list of the factors that you think are important.
The composition of household waste varies widely from country to country. As an example, Table 1 presents data on household waste composition in India and Wales.
Table 1 Household waste composition in India and Wales
| Category | Average of 23 Indian cities (%) | Wales (%) |
|---|---|---|
| Paper | 5.7 | 21 |
| Textiles | 3.5 | 1.8 |
| Leather | 0.8 | |
| Plastics | 3.9 | 7.3 |
| Metals | 1.9 | 5.6 |
| Glass | 2.1 | 5.8 |
| Food and garden waste | 41.8 | 28.4 |
| Other combustible waste | 12.1 | |
| Other non-combustible waste | 12.8 | |
| Ash and other fine material | 40.3 | 5.2 |
| Per capita production | 0.38 kg d−1 | 1.43 kg d−1 |
(Sharholy et al., 2007; Burnley et al., 2007)
Account for some of the differences between the household waste composition in India and Wales, as shown in Table 1.
Policy and legislation depend on how developed a particular country is and on whether geographical constraints restrict the options for waste management. Having said that, the following features are common to many individual countries or groups of countries.
The application of a ‘waste hierarchy’ to define priorities for waste management. Hierarchies vary, but generally follow this structure:
Look at any country’s waste policies and you will probably find a general commitment to reduce the environmental impact of waste treatment. You will almost certainly find a commitment to reduce waste and increase the recycling and recovery of wastes. The policies will also reflect the degree of development of the country. For example, Kampala – the capital city of Uganda – has an aim (not fully met in 2012) of collecting all the city’s municipal waste. In contrast, Germany has the aim of virtually eliminating landfill by 2020 through maximising the recovery of materials and energy from waste.
It may seem rather obvious, but the only reason we have wastes to manage is that society as a whole (including you and me) generates waste in the first place. Going back to pre-history, our nomadic ancestors produced virtually no waste at all, so waste was not a problem for them. Whilst it can be tempting to advocate a return to this golden waste-free age, most of us would not be happy to reject the last 5000 years of progress that humanity has achieved.
Having said that, waste reduction and the reuse of waste can help to minimise the quantities of waste that need to be treated.
The rest of this section will look at examples of both techniques in the home and in industry and commerce.
Virtually all national waste policies (such as those containing the European waste hierarchy) place waste reduction and reuse right at the top. However, in practice the message sent out about waste reduction and reuse is very mixed. For example:
Some countries promote waste reduction through a tax on carrier bags provided by shops. For example, the Republic of Ireland, Northern Ireland and Wales all levy a tax on single-use carrier bags. This is a controversial measure and the environmental benefits are not completely clear-cut, but the measure does send a clear signal to consumers and encourages them to think about the wastes they generate.
So much of waste reduction and reuse in the home is common sense that you are almost certainly already doing this without thinking about it. When you go shopping and answer ‘no’ to the question ‘would you like it in a bag?’, you are taking part in waste reduction. Also, consider the humble jam jar:
Write down ways in which you already practise waste reduction and reuse. Then, based on what you have read or seen, write down some additional steps you could take in the foreseeable future, when practicable, to reduce or reuse wastes in the home.
Looking back to Table 1, you can see that in Wales around 28% of household waste (i.e. the food and garden waste) is readily biodegradable and could possibly be made into compost in people’s gardens. Many local authorities in the UK support home composting through the provision of advice and/or subsidised or free composting bins.
Home composting is an excellent example of waste reduction/reuse. The local authority saves money through reduced collection and processing/disposal costs, and the householder has a free source of material that can improve the quality of their garden soil.
Why would it be unrealistic to assume that Wales can eliminate 28% of its waste through home composting?
Waste reduction/reuse does have the potential to eliminate part of the need for waste management, but it is important to recognise that there are limits to the amount of waste reduction that people will carry out in the home.
The debate in the UK over the relative environmental benefits of using disposable and reusable nappies is an example of this. While the answer to the question ‘which type of nappy is better?’ is far from clear, with disposables performing better in some areas and reusable in others, there is no doubt that a move from disposable to cloth nappies would reduce the amount of household waste produced. However, disposable nappies are very convenient and easy to use and, as such, many consumers will exercise their right to buy and use them.
Similarly, we cannot expect consumers (including you and me) to give up their right to buy pre-washed salads and packaged ready meals (which, while being expensive, are convenient).
Western festivals such as Christmas, Easter and St Valentine’s Day all lead to the purchase of unnecessary, often over-packaged goods with a corresponding adverse environmental impact. Yet perhaps the excess waste is a small price to pay to celebrate these cultural and/or religious festivals while giving pleasure to our friends and families?
Commercial and industrial firms pay directly for their waste to be collected and treated, so reductions in waste have an immediate and tangible benefit to the organisation. In fact, industrial firms pay for their waste three times over:
Furthermore, reducing and reusing waste can help to establish a company’s green credentials.
A commercial company buys 11 tonnes (or 4200 reams) of paper each year at a cost of £840 per tonne. Of this, 30% ends up in letters, reports, etc. that are delivered to customers or stored by the firm’s staff. The rest is disposed of to a waste management company that charges £45 per tonne to collect and landfill the paper. Compare the costs of the following three scenarios:
The relatively simple example in the previous SAQ shows that waste reduction/reuse can achieve a 14% reduction in paper purchasing and disposal costs – in this case, at virtually no cost to the firm concerned.
There are many ‘waste reduction clubs’ and ‘green business clubs’ across the UK whose members can work together and exchange ideas and experiences to reduce waste or other environmental impacts (energy use, water consumption, etc.). Some of these clubs are related to particular river catchment areas, where consultants have been brought in to help identify areas where savings could be made. A few success stories are listed below (WRAP, 2013).
Devising and implementing a waste reduction strategy will vary in complexity with the size of the business and the number of product and feedstock streams it deals with, but there are a number of key stages that are required in any scheme (see the box below).
This section defined waste, and introduced the idea that we should be thinking about wastes as ‘resources’ and focusing on ways of using these resources rather than simply disposing of wastes.
Waste can be classified in many different ways, and the composition of a nation’s waste depends on its degree of development, industrial systems and cultures. Municipal or household waste is one of the most challenging wastes to deal with.
Most countries and/or economic areas have clearly specified policies on waste and its management. Generally, these policies adopt a hierarchical approach to preventing, recovering and treating waste, and seek to minimise the adverse human health and environmental impacts of waste management.