2.6 National Waste Strategy: Scotland Principles

The National Waste Strategy: Scotland establishes key principles, which need to be taken into account in establishing a sustainable future for waste management. A number of these have influenced the development of the Western Isles AWP. These are:

• The Waste Hierarchy
  

• The proximity principle and self sufficiency
  

• Best Practicable Environmental Option.

How these principles will affect the development of waste management systems and methods in Western Isles is described below.

2.6.1 The Waste Hierarchy

The waste hierarchy provides a framework within which the most desirable waste management options are set out. Within Western Isles, in common with the majority of Scotland, existing waste management practices are towards the bottom of the hierarchy. The objective of sustainable waste management is firstly to minimise the amount of waste being produced at source and thereafter increase the percentage of waste that can be reused, recycled and recovered. Ultimately the percentage of waste being disposed of to landfill should continue to reduce.

Waste Prevention
The need to prevent waste, minimise and reuse waste has never been greater. Waste prevention, therefore, forms a key element of the National Waste Strategy: Scotland. Waste prevention can be achieved at a number of stages including pre-product design stage, changes to management and production processes, and the development of clean or ‘wasteless’ technologies.

Waste prevention initiatives must address two distinct waste streams:

• household waste
  

• commercial and industrial waste.

Household waste is by far the greatest proportion of MSW. The prevention of household waste at source will save money in the transport and subsequent management of waste throughout the islands – this money could used for other purposes. Waste prevention can be achieved by the household and businesses through customer decisions about what to buy and how much packaging to accept, and householders choices about how efficiently to use the products they buy and what to do with the products when they are finished – bin them, pass them onto someone who can use them, use them again or use them for something different.

For commercial and industrial wastes there is a great deal of evidence, which demonstrates that waste can be significantly minimised at various stages of manufacturing processes providing both a financial benefit to the company as well as reducing the environmental impact of waste. Local companies in the Western Isles could become more efficient and, therefore, more competitive by addressing waste prevention in a systematic way.

Waste prevention can be achieved by the household and businesses through customer decisions about what to buy and how much packaging to accept, etc., and householders choices about how efficiently to use the products they buy and what to do with the products when they are finished – bin them, pass them onto someone who can use them, use them again or use them for something different.

In recent years there has been a decline in the reuse and refurbishment of consumer durables as the cost of replacing them has fallen in relation to the cost of repair. However, as well as removing items from the waste stream, reuse and refurbishment are linked to job creation and economic improvement. There are already reuse and refurbishment schemes in operation in Western Isles, ranging from the reuse of old clothing through to the use of old scallop shells as a drainage material. It is considered that there remains potential for future expansion and opportunity for stimulating this type activity in Western Isles.

Recycling, Composting and Anaerobic Digestion
Recycling is the separation of a material for processing, followed by preparation and sale onto a market to replace an existing virgin material. The most commonly recycled materials include newspaper, cardboard and glass. As such there are often numerous environmental benefits, such as reduced air emissions, reduced impacts of extraction, energy savings, lower disposal impacts and more efficient use of raw materials. There are often other benefits such as encouraging producers to take responsibility for their wastes and economic benefits such as improved competitiveness or greater employment opportunities. The collection of wastes as separate material fractions reduces contamination and the need for additional separation processes. This retains the quality and value of the waste materials.

Composting is the aerobic decomposition of organic material to produce a stable material containing organic matter and plant nutrients. There are often benefits in applying this material to land, including nutrient addition, improved soil structure and improved water retention. These benefits are often only realised through the use of source segregated uncontaminated compostable wastes.

Anaerobic digestion (AD) is a similar process to that of composting, except the micro-organisms degrading the waste operate in an oxygen-free environment – i.e. where composting processes focus on enhancing conditions for micro-organisms that thrive in the presence of oxygen, AD targets those that thrive without. AD systems, in fact, often also incorporate an element of composting, in order to ‘mature’ the end-product into a high quality ‘digestate’. The potential advantage of AD systems is that methane gas is produced as a by-product of the degradation process, and this can be used not only to fuel the operation of the plant, but typically also to power other processes in the vicinity. As with composting, the AD process generates a useful end product (the digestate), which can be applied to land to improve soil structure and growing conditions. AD systems can be more complex and therefore more expensive then composting, and this is particularly so at very small scales (i.e. <3000 tpa waste throughput) where composting becomes most cost-effective.

The BPEO for MSW put forward by this plan will significantly increase the amount of this type of waste that is recovered by recycling, composting and anaerobic digestion. Future plans for other, non-MSW streams will also seek to provide integrated cross-sector solutions and increase the proportion of total waste arising that is recovered by these various routes.

Other Recovery
Other recovery involves recovering part of the energy value from waste, either by burning or thermally treating the waste directly (for example incineration) or by burning a fuel produced by the waste (as with Refuse Derived Fuel or landfill gas). The energy conversion efficiency of the plant will depend on the specific design, e.g. recovery of energy through combined heat and power.

SEPA has consulted on their “Guidelines and approach to thermal treatment and energy from waste” in the summer of 2002 and these guidelines will be reviewed in light of the consultation before its final launch. For further details refer to SEPA’s final “Guidelines and approach to thermal treatment and energy from waste”, available at www.sepa.org.uk/nws.

Waste Disposal
Landfill disposal sits at the base of the waste hierarchy for the following reasons:

• potential pollution to land, air and water
  

• it is a waste of resources and is considered to be unsustainable.

Landfill will, however, continue to form part of an integrated waste-management system of treatment and disposal options for the foreseeable future.

2.6.2 The Proximity Principle and Self-Sufficiency

This means waste should be disposed of as near as possible to the point at which it arises. Most of waste originating in Western Isles is managed within the area, with the exception of wastes requiring specialist treatment, such as hazardous wastes, and wastes being sent to the mainland for recycling, e.g. scrap metal. These wastes are often then subsequently transported as far as the south of England. Although this is likely to continue to be the case to some extent, as greater quantities of material for recycling are collected then there will be more opportunities for the development of local markets and reprocessing facilities in Western Isles.

Due to the isolation of the islands, and the associated exceptional high cost of waste transport, the principles of proximity and self-sufficiency have been the two key drivers in developing the area’s BPEO.

2.6.3 The Best Practicable Environmental Option (BPEO)

BPEO is the outcome of a systematic and consultative decision-making procedure, which emphasises the protection, and conservation of the environment across land, air and water. The BPEO procedure establishes, for a given set of objectives, the option that provides the most benefits or the least damage to the environment as a whole, at acceptable cost, in the long term as well as in the short term. As applied by national guidelines this includes balancing social, economic and environmental costs and benefits. The Western Isles AWP describes the BPEO for MSWs and sets out the process by which the BPEO will be determined and implemented for all other wastes. The process of assessing the Western Isles BPEO placed particular emphasis on proximity and self-sufficiency, and the need to recover as much value locally, to provide social and economic benefits.