Composting of a Mixture of VFG Waste and used Paper Diapers

Abstract

Waste disposal in the Netherlands has come under great pressure in recent years. The policy of the Dutch government is directed towards radically restricting on the domestic waste to be dumped on the basis of social, spatial and environmentalprotection considerations.

At present, however, paper diapers are thrown into the rubbish bin (grey container) and then dumped or incinerated. The used paper diapers largely consist of pulp and are therefore in principle suitable for being composted together with normal Vegetable, Fruit and Garden (VFG) waste.

Various studies on the compostability of a VFG waste/paper diaper mixture have demonstrated that a good-quality compost can be produced from it.

However, the used paper diaper also contains approx. 15 wt. % plastic film in addition to the compostable material. This plastic diaper film must not end up in the final product. It is therefore anticipated that an adjusted process route will be necessary for composting VFG waste/diaper mixtures.

The Department of Environmental Technology of the Institute of Environmental and Energy Technology (TNO-ME) in collaboration with the Research and Development Department of VAM has carried out a study to develop an adjusted process route for composting VFG waste/diaper mixtures. The point of departure for this adjusted process route is the composting process applied at VAM. The following process steps have been added to this VAM process and studied. Prior to composting:

• Screening of the VFG waste/diaper mixture over a 60 mm screen to remove all diapers from the VFG waste.

• Grinding of the screen fraction > 60 mm (mixture containing all paper diapers and coarse VFG waste).

After composting:

• AircIassifying/screening of the screen fraction> 25 mm to remove the plastic>diaper film.

The results of this study are as follows:

• Mixtures of VFG waste and used paper diapers can be composted without difficulty by introducing additional process steps. The quality of the agricultural compost produced from the VFG waste/diaper mixture via this adjusted process route is good, and the quantity of plastic diaper film in this final product is very low (0.04%) and not visually disturbing.

• The quantity by weight of used paper diaper waste to be dumped or incinerated is reduced by approx. 84% as a result of the composting of the used paper diapers. What remains as waste after compo sting of the used paper diaper is the plastic diaper film. This accounts for approximately 16% of the weight of the used paper diaper. The plastic diaper film can be separated out as residue to 98% as a result of the introduction of the additional process steps.

In the context of integrated waste treatment in the Netherlands. the benefits resulting from the composting of used paper diapers can also be presented as reduced incineration costs. This can signify a cost saving of up to 10 million guilders per year on the waste treatment of used paper diapers, and a further increase in the future.