Recycling of municipal organic wastes from separate collection systems becomes more and more important in the Federal Republic of Germany. Experiences gathered during the last few years indicate that the recovery potential of waste and biosolids strongly depends on quality of the produced composts or their pollutant load. This means that only really low polluted composts will be competitive in the recycling market. These materials have to fulfil the demands recently given by the so called 'Biowaste Regulation (Bioabfallverordnung)' which has been passed in September 1998. Consequently only these materials can be recycled which, compared to the values given in Table 1, show a lower pollutant load. To keep or better to improve the quality of the composts educational (pollutant detection at the collecting device) and technical steps can be implemented. One promising technical step is an 'extended treatment' which is based on the well known two step digestion process. Theoretical possibilities for such an 'extended treatment technologies' are:
- mechanical separation of higher polluted fractions
- physical-chemical separation of inorganic pollutants (heavy metals) by adsorption, leaching, precipitation/flocculation
- biological-chemical reduction of organic pollutants
Using one, two or three of these possibilities in combination an extended reduction of the pollutant load should be achievable especially for highly polluted organic wastes.