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Dealing with Unavoidable WasteUnavoidable wastes are the mixed wastes remaining after ‘Stretching Best Practice’ in reuse, recycling and composting. Specifically, they are:
Categories of Unavoidable Wastes Unavoidable wastes arise from households, commercial premises and industrial activities (which include construction and demolition). Unavoidable wastes can be considered in three broad categories, reflecting the degree of potential environmental impacts, for strategic management purposes Inert Waste This is mainly construction, demolition and excavation
wastes. It is the largest waste category and is essentially inert.
Whilst it can give rise to environmental problems, the extent tends to
be much less than with other waste categories. Non-Hazardous Waste This is general waste including household and
commercial wastes. It contains a wide range of different materials
(paper, metals, plastics, food and vegetable matter, wood, etc). Much of
it is biodegradable and has the scope for significant environmental
impacts unless properly managed. Hazardous Waste These materials pose a particular threat to human health and/or the environment and require special management care. Relatively small volumes of hazardous waste arise when compared to the other categories.
Unavoidable Waste Volumes After taking account of the proposed target of reducing growth to 0.5% by 2020 (see Increasing Resource Efficiency and Reducing Wastage) together with the recycling target of 60% (see Maximising, Reuse, Recycling and Composting), there will still be an estimated 2.7 million tonnes of unavoidable waste requiring treatment and/or disposal in 2020. This is the best case scenario based on achieving ‘Stretching Best Practice’ in waste reduction, reuse, recycling and composting.
Landfill has been the main overall disposal method. Whilst modern landfills are engineered and regulated to minimise environmental impacts, landfill disposes of potentially useful material with no value being recovered (other than landfill gas in some instances). In addition, there are increasing local and national constraints on landfill as an option:
Project Integra responded to the historic local landfill shortage by investing in a new processing infrastructure, including three energy recovery incinerators, for unavoidable municipal waste. These facilities will have taken over ten years to plan, consent and construct by the time they are fully running in 2005. In contrast, the private sector, who deal with the vast majority of commercial and industrial wastes, have resorted to the lowest cost option by hauling waste increasingly longer distances for disposal by landfill. It is currently estimated that about two thirds of hazardous and non-hazardous commercial and industrial wastes are exported to other counties for disposal. This may quickly become a less attractive option financially as fuel prices, traffic congestion and landfill taxes increase and landfill sites become increasingly scarce. There is a need to change our approach for all types of unavoidable waste management. This means moving it up the waste hierarchy and recovering materials and energy rather than relying on landfill. We should aim for net self-sufficiency for unavoidable waste treatment and disposal by 2016. This date coincides with that in the Regional Waste Strategy for London being self-sufficient other than for residual landfill. Unavoidable waste should therefore be managed in accordance with the following principles:
The need for sorting / pre-treatment will depend on the waste type and the level of source segregation previously applied to it. It is estimated that about 10-20 new medium to large scale sorting/pre-treatment facilities may be required with a total capacity of 2 million tonnes per annum. Specific management arrangements are considered in
more detail below under the classifications of inert, non-hazardous and
hazardous wastes. Inert Waste Management Since the majority of this material was dug from the ground and is non-biodegradable and non-flammable, the only realistic disposal option is landfill. Landfill should therefore be the disposal option for those inert wastes that cannot be practically reused or recycled. There will be an estimated 0.8 million tonnes of inert waste requiring disposal in 2016 and 0.7 million tonnes per annum by 2020. This equates to about 2-4 inert landfill sites depending on how much could be beneficially reused and the size of site. It would be expected that the waste entering such sites will have been subjected to pre-treatment, either on-site or remotely, to maximise the removal of recyclable contents and segregate inert from non-hazardous wastes.
It is estimated that about 2 million tonnes per annum of unavoidable non hazardous waste (excluding construction, demolition and excavation waste discussed above) will require disposal in 2016, reducing to about 1.8 million tonnes per annum in 2020. Having regard to the continued availability of existing infrastructure, additional resource recovery capacity for non-hazardous wastes should be provided by 2016. This is equivalent to about 4-6 major resource recovery facilities. There are various processing and recovery technologies that can be utilised for these wastes. Some of these are tried and tested technologies whilst others are to some extent unproven operationally in the UK. They fall into two main categories:
A mix of options can be used to make up an overall solution. For example, a generic technology known as mechanical biological treatment (MBT) can involve pre-sorting, biological treatment and combustion of the product as a fuel. Options further divide into those that process waste as delivered (e.g. the existing energy recovery incineration process used by Project Integra) and those that require the input to be mechanically sorted and/or shredded to produce a more consistent feedstock to feed into subsequent thermal or biological processes. The products recovered from these processes include energy, materials and low-quality soil-like materials. As a last resort the latter may be disposed of to landfill but it is currently uncertain whether or not they will be classed as non-biodegradable for the purposes of the Landfill Directive. The ability to secure sustainable long-term outlets/markets for the products varies between the options and is a critical factor to consider when assessing appropriate technology. Given the contaminants inherent in mixed waste and the very restricted availability of long-term markets, there is currently less risk in maximising the direct energy recovery potential rather than producing a poor quality soil conditioner or a fuel for which there are limited outlets. Maximising the energy recovery potential of waste, and thus its potential to replace fossil fuels, is likely to have an increasingly important role in future as fossil fuels supplies come under pressure. This approach favours the linking of energy recovery incineration to the supply of heat as well as electricity, thereby maximising energy efficiency or, subject to affordability and reliability being demonstrated, the use of emerging processes such as gasification and pyrolysis. The latter technologies use a prepared feedstock and have potentially better energy efficiency and lesser emission volumes. It is sometimes argued that adopting options like energy recovery incineration can inhibit recycling. Project Integra and many European communities have demonstrated that this is not the case when proper attention is given to sizing of facilities. In fact, communities that have incinerators also tend to have high recycling levels. The co-processing of household, commercial and industrial wastes would be a further safeguard against any possibility of this happening. Project Integra has invested in three new energy recovery incinerators. The plants were sized to deal with 75% of the then unavoidable municipal waste stream. There have however been important developments since the Project Integra Municipal Waste Management Strategy was agreed in 1996, that mean that more processing capacity will be needed by 2020:
To meet the need for additional resource recovery capacity, new technologies such as gasification, pyrolysis and anaerobic digestion should be considered. In Europe there are many examples of these systems in use. However, they operate under different legislation, tax regimes and regulatory regimes to the UK. No large scale new technology applications are currently established and proven in the UK. Very careful analysis would be required before any decision was taken to introduce them here. Further large scale thermal treatment capacity, via mass burn or fluidised bed incineration, may therefore be required to meet future needs. This option, combined with stretching best practice in recycling, could increasingly be the best value solution as Landfill Tax increases and landfill sites become increasingly scarce. Incineration produces incinerator bottom ash (IBA) that is suitable for recycling into aggregate. Trials on the use of the material are encouraging and the IBA from the three Project Integra plants has the potential to replace over 100,000 tonnes annually of crushed rock. The recycling of IBA should be maximised and a site for processing it into aggregate identified. In addition, supporting landfill capacity for disposal of non-hazardous wastes and residues will also be needed. The need is for capacity to handle 0.8 million tonnes per annum, equivalent to about 2-4 non-hazardous landfill sites. It would be preferable if capacity to pre-sort / pre-treat unavoidable wastes was co-located at facilities for resource recovery or disposal.
Hazardous Waste Management Hazardous wastes are generally managed on a national or regional basis given the relatively small volumes and the specialist facilities needed. There are approximately half a dozen licensed hazardous waste facilities in Hampshire; many of these sites accepting wastes from across the country. Other wastes are exported out of our area for treatment/disposal. The Landfill Directive has prohibited the co-disposal of hazardous and non-hazardous wastes at the same landfill site. There is now only one hazardous waste landfill in the South East. Despite this, it is unlikely that a hazardous waste landfill site could ever be developed in Hampshire given the environmental constraints, limited arisings and uncertainties over the hazardous waste market. In order to move towards net self-sufficiency for all wastes, we have to take into account the amount of hazardous waste presently exported, seek to focus minimisation efforts on exported wastes, and encourage expansion of existing capacity where appropriate. There are two major hazardous waste streams where additional management capacity is needed:
The provision of a ‘soil hospital’ to decontaminate soils would help to address hazardous waste capacity issues. There is a need for a specialist recovery/disposal facility for air pollution control residues (fly-ash) to be provided on a national or regional basis.
In summary there is likely to be a need locally for 14–26 new sorting / treatment / recovery facilities and 4-8 new landfill sites. The waste management industry should start to provide new local resource recovery and treatment facilities for commercial and industrial wastes. However, creating favourable conditions for the necessary investment is a major challenge. Unlike municipal waste, the capital investment cannot be underpinned by long-term waste service contracts and there is, therefore, a higher business risk. Also processes that are as yet unproven in the UK or have no guaranteed long-term outlets for their products are unlikely to attract investment. Rather than be prescriptive about processing/treatment technologies for this sector, it is more appropriate to leave the choice of technology to market forces, subject of course to any proposals meeting the required environmental and public health standards. In order to foster a climate in which business can invest in such technologies, it is important to limit the opportunity for landfill by only meeting essential unavoidable waste disposal needs. Such limitations are imposed naturally as a result of our hydrogeological and environmental constraints, and it is unlikely that more than a few potential sites suitable for the landfilling of non-hazardous wastes could in any event be found. It is important however to be pro-active in encouraging the integration of household, commercial and industrial waste management systems. Resource recovery capacity for commercial and industrial wastes could also be created by taking advantage of synergies with municipal waste. The latter is under local authority control and there is therefore scope to plan more widely so that suitable commercial waste, with similar characteristics to household wastes, could be accommodated within existing or new infrastructure. This could reduce the cost of managing municipal wastes through improving efficiency. Opportunities for the co-processing of non-hazardous municipal, commercial and industrial waste streams should be investigated. There is scope for bringing forward the provision of additional capacity and accepting commercial waste at a market rate in order to balance the system, taking account of actual waste growth and recycling achievement. Similarly, it may be possible to accommodate municipal wastes from other authorities. This would counter-balance ongoing export of hazardous wastes in order to meet our targets for net self-sufficiency.
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