More than 10 million tonnes of UK waste is incinerated in energy from waste plants each year, making a considerable contribution to UK energy demand. The emissions from waste incinerators are regulated by the Environment Agency through the Environmental Permitting Regulations which sets stringent emission limit values for a wide range of pollutants, including, particulate, VOCs, CO, HCl, HF, SO2, NOx, heavy metals and dioxins/furans. The emissions control system for waste incinerators represents a major proportion of the capital and operational costs.
The emissions of dioxins and furans from waste incinerators into the atmosphere are of considerable public, political and scientific concern. The issue around dioxins/furans is associated with their high toxicity, significant health hazard and resistance to degradation in the environment. Dioxins/furans cause damage to the human immune, nervous and reproductive systems and are also suspected carcinogens. There is consequently concern over the negative effects on human health and the environment of long-term exposure to even very small amounts of dioxins/furans.
Impending legislation under the EC Industrial Emissions Directive that will be transposed into UK Law via the Environmental Permitting Regulations has set mandatory stringent new Daily Emission Limit values for waste incinerators. Dioxin/furan emission limits are to reduced from 0.1 ng m-3 to 0.01 ng m-3 for most incinerator installations. The current most common method for control of dioxin/furan emissions uses added activated carbon reagent for the adsorption of the dioxins/furans from the flue gas followed by capture using fabric filter bags. The use of activated carbon is a high cost method and merely transfers the dioxins/furans to the flue gas control residue and subsequent disposal to high cost hazardous waste landfill.
The aim of this research proposal is to develop a novel, low cost, low temperature (~150 C), non-thermal plasma-catalyst process to decompose dioxins/furans under flue duct conditions simulating those of typical waste incineration flue gases. A complementary study using model chlorinated aromatic model compounds will aid a mechanistic interpretation of the decomposition of dioxins/furans under non-thermal plasma-catalysis conditions, aiding the development of the dioxin/furan control system.