2007:04 Hantering av förpackat livsmedelsavfall - Avfall Sverige

DEWASTER ® - Sorting out the problems of mixed waste
General presentation.
The DEWASTER® system is a novel solution to the treatment of mixed waste streams containing
a significant proportion of bio-degradable material, such as Municipal Solid Waste (MSW),
Organic Fractions of Municipal Solid Waste (OFMSW) and Commercial Food Waste (CFW).
The DEWASTER® system is build around the unique DEWASTER ® screw press which separates
plastic, paper, long fibres and other foreign matter from OFMSW to extract the bio-degradable material
as a pure bio pulp suitable for anaerobic co-digestion with sewage sludge, animal slurry or industrial
organic waste.
The DEWASTER® screw press was originally developed for additional sorting and conditioning of
OFMSW for use in bio gas production. The first unit was delivered in spring of 1999 to a bio-gas plant
involved in trials with processing of source sorted household waste originating from the municipality of
Aalborg and number of surrounding municipalities in Jutland, Denmark. A short overview of the history
and the objectives off the development of the DEWASTER ® - system is included in appendix 1.
In addition to the DEWASTER® screw press, a further range of auxiliary equipment including bagopeners,
shredders, drum sorting or screen sorting equipment, metal separators and containers which
allows for a highly automated treatment of not only OFMSW, but also unsorted MSW and CFW has
been developed. The basic purpose of the DEWASTER® process is the separation/sorting of mixed
waste streams into its constituent parts, in particular the following fractions:
• Pre-sorting reject consisting of paper and plastic “fluff” low in ash and chlorine and suitable for coburning
in cement kilns and power plants.
• Metals suitable for recycling.
• Press reject from the DEWASTER® screw press consisting of some organic matter and fibrous
materials and suitable for disposal through composting and use as cover material in landfill or incineration.
• Bio pulp with 25-30 % dry matter, free of all fibrous long particles and other foreign matter, generally
low on heavy metals and other pollutants and suitable for anaerobic co-digestion, e.g. in bio
gas production.
An example of the process design and the results obtained in using the DEWASTER® process on
unsorted MSW is included in appendix 2.
Through the separation process the DEWASTER® system enables targeted, cost efficient and environmentally
friendly recycling, recovery and disposal operations for each part of mixed waste streams,
in particular extended possibilities of co-burning and the recovery of the energy potential of OFMSW
through bio gas production, a goal typically not achieved in composting operations and/or traditional
landfill. The DEWASTER® system thereby presents a novel opportunity for achieving the diversification
objectives of the EU landfill directive and/or to save on investment in new incineration facilities.
A number of full scale trials with the DEWASTER® technology with both source-sorted and unsorted
waste have been carried out a in Denmark and abroad and several commercial units were build and
commissioned. A list of major reference projects is included in appendix 3.
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