The undersized fraction

landfills, municipal waste, recycling, waste disposals, sorting plants


As a result of the global trend to cut down disposal of waste containing organic components, the number of Mechanical Biological Treatment (MBT) for sorting the municipal waste is rising. There are many technical solutions and configurations of MBTs according to customers' requirements. But in the first place, all MBTs are designed for recycling and utilization of separated materials.

The separated fraction of residual waste containing organic components is called the undersized fraction. This fraction is eliminated by means of landfilling or incineration, which is economically inefficient. By processing this fraction in aerobic fermenters EWA/BEWA integrated after the mechanical part of the MBT, it is possible to produce, under controlled conditions, an alternative certified fuel FEBISKOPAL. The refining process is in comparison with commonly used methods shorter and low-energy.


The increase in trash is due to population growth and consumerism. Landfills and the surrounding areas are often heavily polluted. It is difficult to keep dangerous chemicals from leaching out into the surrounding land. Landfill can also attract animals and insects to come such as raccoons, rats, mosquitoes, cockroaches, and seagulls. And moreover, it can also cause sicknesses, illnesses, and diseases which might spread in communities.


The world's trend is to reduce landfilling of usable waste containing biological components. That is why the number of facilities separating the municipal waste (MBT - Mechanical Biological Treatment) is rising. There are various types of custum-made MBTs. The municipal waste is crushed and separated. The remains of separated municipal waste with biological components found under the sieve are called the undersized fraction. This fraction is landfilled or burnt in incineration plants in an economically non effective way.

Toughening limits for accepting waste on disposals, especially of the waste containingbigger part of organic components, has brought transportation problems due to greater distances from incineration to disposal site. This involves bigger environmental burden because of emissions from transport of waste. In Czech republic, energetic utilization of the undersized fraction and elimination of waste in incineration plants is significantly economically more challenging than landfilling.

The undersized fraction must not contain materials that can change the fuel properties, can have impact on its energetic use or can have negative impacts on the environment.

The undersized fraction producer has to guarantee, that the input material is not explosive, toxic, infectous, carcinogenic, caustic, ecotoxic and it is not injurious to health. It must not be contaminated by waste classified as hazardous.

The undersized fraction suitable for processing in EWA fermenter according to the EUROPEAN WASTE CATALOGUE AND HAZARDOUS WASTE LIST

    • 19 12 10 combustible waste (refuse derived fuel)
    • 19 12 12 other wastes (including mixtures of materials) from mechanical treatment of wastes other
    • than those mentioned in 19 12 11 ( 19 12 11 other wastes (including mixtures of materials) from mechanical treatment of waste containing dangerous substances)


Approximate composition of the undersized fraction for the fuel production at the time of separation:

  • biodegradable municipal waste 40%-60% of the weight
  • combustible non compostable waste 10%-30% of the weight
  • Inert and non incinerable admixtures 15%-30% of the weight


Mixed municipal waste components specifications:

Biodegradable municipal waste (BMW)

Consist from plant and animal origin residues and paper. Plant residues are vegetable scraps, leftovers from coffee and tea, grass, leaves, flowers, remnants of weeding flower beds, vegetable textile fibres, wood grown and construction, paper and cardboard, and more. Animal waste includes residues from food preparation and household leftovers, animal origin household leftovers and expired food, animal origin fibers, used oils and edible fats. Packaging paper, hygiene paper, newspapers, magazines and advertising paper.

Combustible non compostable waste

Consists from tiny pieces of plastic, foils, polystyrene, industrial synthetic fibres, agglomerated plates pulp and rubber and more.

Inert admixture

Consists mainly of glass, metal residues, brick, stone, ceramics, ash, sand and soil.


The fuel production consist of refining obtained undersized fraction in EWA fermenter. The refining process takes place in the aerobic fermenter EWA using the invention "The way of converting hygienically non stabilized biodegradable substrate to hygienically stabilized product", patent number 295922 CZ, that is the in-vessel composting process. It is possible to employ a sieve afterwards in order to separate inert parts (sand, soil) and reduce ash content.

The in-vessel aerobic fermentation process side effect is decrease of the bad smell and health risks. Material is stabilized and hygienized thanks to temperatures over 65°C during the process.

The alternative fuel from refined undersized fraction can be burnt in energy facilities, excluding facilities with low production.




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