Hampshire, Portsmouth and Southampton
Minerals and Waste
6.26 Resource recovery is the use of mixed waste as a source of materials and/or energy. In this way the resource value of waste can be realised and the volume of waste requiring final disposal reduced. The Councils believe that waste materials for which recycling is not practicable should, wherever feasible, be processed by resource recovery systems. It is mainly the biodegradable and combustible household and commercial waste materials that have resource recovery potential. National policy advises that using waste to supply useful energy is a well-established method of adding value before final disposal and will increasingly represent the best practicable environmental option for many wastes.
6.27 Resource recovery from mixed waste can be carried out by means of the following processes:
A. Low Technology:
(i) Materials Recovery Facility - mechanical and/or manual sorting and recovery of dry recyclable materials.
(ii) Aerobic Composting - suitable for 'green' (garden) waste only; produces soil conditioners and mulches.
(iii) Landfill Gas Collection - only realistic at large landfill sites where a collection system is planned from the outset.
B. High Technology:
(iv) Anaerobic Digestion - suitable only for organic waste; produces biogas for use as a fuel (e.g. for electricity generation and/or district heating), a liquid which can be used as a fertiliser and compost suitable for use as a soil conditioner.
(v) Refuse Derived Fuel - shredding and screening of waste to remove incombustible materials and produce a fuel for use in industrial boilers or for electricity generation and possibly also for district heating.
(vi) Energy from Waste Incineration - combustion of waste and use of heat for electricity generation and possibly also in district heating.
(vii) Gasification - conversion of organic waste material to gas by partial combustion at high temperature.
6.28 The use of materials recovery facilities and aerobic composting form part of the Hampshire Household Waste Management Strategy, and such facilities have already been established in Hampshire. Landfill gas collection is unlikely to be feasible on any significant scale in Hampshire given that the geology of the County is not suited to the establishment of large new landfill sites. However, small-scale recovery may be possible at some locations. Gasification is an emerging technology which may eventually prove to be an improvement upon other available methods of waste processing. However, it is not yet proven as a method for dealing with household waste and is not an option for the period covered by the Plan. The County Council has been assisting a local company with an experimental gasification scheme and it is hoped that this technology will contribute to the next generation of waste management systems.
6.29 Anaerobic digestion can only deal with biodegradable waste (up to about 50 per cent of household waste) and generally requires pre-separation of the waste stream to remove non-organic materials if a useable soil conditioner is to be produced. There are a few anaerobic digestion plants in operation elsewhere which handle household waste but the technology has not yet been fully proven for large volumes of waste. The annex to PPG 22 on anaerobic digestion states that, whilst municipal solid waste is suitable for processing by anaerobic digestion, it is currently uneconomic to do so and there is no obvious market for the digestate. In the immediate future this technology may be more appropriate for the digestion of other wastes, for example sewage sludge and farm slurry. However, there may be opportunities for co-operation between waste disposal operators and sewage disposal operators through the provision of anaerobic digesters for the processing of household waste and sewage sludge. Such systems could form part of an overall strategy for waste management, subject to further investigation and affordability. Regard should be had to this potential in the location of waste processing plants. Refuse derived fuel has the theoretical advantage of enabling the flexible use of waste as a fuel without the need for a dedicated combustion plant. However, in practice there have been significant problems in the marketing and use of refuse derived fuel and many plants have had to close. The process also suffers from the need to sort the waste and the fact that about 40 per cent of waste by volume remains after processing and must be landfilled.
6.30 Energy from waste incineration involves the combustion of mixed waste with the heat released being used to raise steam. This can be used for district heating and/or used to power electricity generating turbines. Ferrous metals can be recovered from the residues for recycling. Residues, comprising fly-ash and furnace ash, total only about 30 per cent of waste input (by weight) and require disposal by landfill. In some European countries furnace ash is used as a construction material, but the possible environmental implications of such use needs to be carefully considered. Fly-ash is potentially polluting and must be disposed of at suitable landfill sites. Refuse derived fuel can also be used to produce energy from waste by incineration. The technology involved in energy from waste incineration is well proven, with many modern plants in operation throughout the world.
6.31 The Councils recognise that there is public concern about the possible environmental and health effects of incineration of household waste, particularly from atmospheric emissions and the landfilling of residues. However, they believe there is now sufficient scientific evidence, together with practical experience from the operation of incineration plants, to be confident that modern incineration processes are safe and do not pose environmental danger. Atmospheric emissions from incinerators are controlled by the Environment Agency and stringent new emission standards have been brought into operation. Disposal of residues at landfill sites is strictly controlled, also by the Environment Agency. Only sites where the disposal of such wastes would not cause pollution would be permitted. Environmental statements accompanying planning applications for energy from waste plants should include, where appropriate, information on relevant accumulated environmental contamination.
6.32 Whilst there are a number of potential systems for the recovery of resources from household and commercial waste, at the present time it appears that energy from waste incineration is the only type of process which has the proven capability of being able to deal with the bulk of such waste in an environmentally acceptable manner. This form of waste processing is strongly supported by the Royal Commission on Environmental Pollution in its Seventeenth Report 'Incineration of Waste' (1993). However, the Councils believe that other types of system are also likely to have a role to play. In the short to medium term, anaerobic digestion would seem to be the most likely other process that may be a practical option, and refuse derived fuel plants may also be a possibility. In addition, aerobic composting and materials reclamation facilities are likely to be an important part of an overall waste management strategy. The Hampshire Household Waste Management Strategy (1994) proposes that resource recovery processes should form part of an integrated approach to waste management in which the range of available options is harnessed to provide an overall solution. The Councils consider that waste minimisation, re-use, recycling and recovery are complementary waste management options. The Hampshire Household Waste Management Strategy seeks a flexible approach through which waste minimisation, re-use and recycling can be maximised. The policies of this Plan set out a land use planning framework which encourages the achievement of this objective.