The EC Landfill Directive is seen as providing the principal legal framework influencing municipal solid waste ( MSW ) management and strategy development in the UK . The most significant part of the Directive proposes a strict timetable for reductions in landfilling of Biodegradable Municipal Waste (BMW).

The importance of this issue and the UK ‘s adherence to this timetable is being hammered home by the UK Environment Agency (EA). On 12 September, the EA reminded businesses and industry of the changes in landfilling waste that come into play from 30 October. Liz Parkes, Head of Waste at the Environment Agency, commented ‘The changes to the rules mean waste must be treated before it is landfilled, and all liquid wastes will be banned from landfills….These changes, which are being introduced under the Landfill Directive, aim to help reduce our dependency on landfill, as well as improve the environmental standards for the wastes that continue to be landfilled.’

As a result local authorities and waste management companies have been increasingly looking to alternative non-landfill solutions for the management of municipal waste to help achieve the Landfill Directive targets. Naturally this has prompted a shift toward the collection of recyclables either in separate containers or increasingly in a co-mingled state.

Kerbside schemes that involve the co-mingled collection of recyclables require a high degree of diligence to be expended by the community and unfortunately just a few individuals ignoring the call for due diligence can thwart the efforts of those that are dedicated to ‘doing the right thing’. Furthermore households are not the only stakeholders in this chain. Indeed, the knock-on impacts felt by the recycling industry to co-mingled collection have prompted a ‘Campaign for Real Recycling’ to be launched earlier this year. The campaign is calling on government and local authorities to urgently review and improve the quality of recycling in the UK . When combined with the problems inherent in allocating space for more than one wheelie-bin per household in busy inner city areas, it is clear that – though a high degree of success can be claimed in this area – the costs of co-mingled collection are significant.

One solution to these problems that is attracting increasing attention in the UK is the thermal treatment of mixed waste through an autoclaving process. The company 3NRG Waste Management expects to have its first commercial autoclave MSW treatment facility, together with an integral power generation plant, up and running in Bridgend, Wales in the third quarter of 2008. The site is an existing closed landfill and holds a license to accept 100,000 tonnes per annum of municipal and commercial waste.

Building the plant – an international venture

Prestige Thermal Equipment, PTE, based in South Africa , has been appointed by 3NRG to build the Bridgend plant which will be a particularly robust and environmentally friendly facility. PTE possesses broad international industry experience in the design and construction of thermal process technologies. The equipment for Bridgend has been designed to be accommodated within existing buildings at the site.

A twin autoclave system will operate at a temperature of 160 degrees C, at 5.2 bar pressure and will effectively cook and prepare the waste material for ease of downstream separation where the equipment is presented with sterile clean recyclables. Well tried and tested robust separation equipment, similar to that employed in the metals recycling industry will be used.

A combination Dryer – Pyroliser – Oxidation unit provides energy to fire a twin boiler system, each boiler being capable of producing 12½ tonnes of steam at the required temperature and pressure. These boilers provide steam to drive the turbine, nominally rated at 5MW. The steam required for the autoclave process is delivered by the hot gas boiler, thus eliminating the need for an alternative fuel source once the plant is operating at steady state conditions. 4MW of the 5MW power produced by the plant will be available for export to the National Grid.