Dioxin/furan formation and release in the cement industry.

Cement kilns firing hazardous waste are explicitly mentioned in the Stockholm Convention as an "industrial source having the potential for comparatively high formation and release of these chemicals to the environment". The substitution of fossil fuels with alternative waste derived fuels is a well-developed practice in a number of countries. In the European cement industry about 6 million tonnes are used which corresponds to a thermal substitution rate of 17%. The current study evaluates around 2200 dioxin/furan stack emission measurements collected from various sources. It is demonstrated that most cement kilns can meet an emission level of 0.1ngTEQ/Nm(3) if primary measures, i.e. process-integrated measures, are applied. Reducing the temperature to a level lower than 200°C at the inlet of the air pollution control device is the key factor which has shown to limit dioxin formation and emissions at all types of cement kilns, independent of waste feeding.