Aims

The aim of this project is to demonstrate that it is possible to safely compost many of the wastes produced by people, industry and agriculture, as a sustainable alternative to landfilling. The composts created can then be used to restore derelict post-industrial sites or to return organic matter and nutrients to degraded agricultural land.

There are 2 main aims of the composting theme of this research:

1. To generate high value ecologically suited soil material for habitat restoration
2. To remove pollutants from contaminated soil

1. Composting for habitat restoration

Composted waste materials represent a valuable resource for restoring habitats of high biodiversity value at post-industrial sites. With the compost that we create from waste materials, we will re-vegetate trial and demonstration areas within a former steelworks site alongside the Dee Estuary (see Shotton). We will also demonstrate how composted waste materials can be used to restore native grass and heather moorland species to parts of the uplands of North Wales that have previously been quarried for slate (see Quarry).

2. Composting for contaminant stabilisation and removal

The EU landfill directive (1999) drastically reduced the number of landfill sites licensed to receive contaminated soil from industrial sites. Instead, waste soil can be composted with other waste materials (see Feedstocks) to remove or stabilise the pollutants that may be present. The high biological activity that occurs during composting can lead to the destruction of organic pollutants, such as some aromatic hydrocarbons. Heavy metals cannot be destroyed during composting but can be strongly bound to high molecular weight organic molecules such as lignin present in organic wastes. We are investigating the mechanisms by which important pollutants are immobilised or broken down and under what conditions the stabilised pollutants may be re-mobilised. To do this we are following the fate of important organic and heavy metal pollutants, such as benzene and cadmium, during composting and after the compost is applied to land.