Dried Sludge Odours: Classification and Case Study

The off-gases emitted by a sludge drying model pilot plant simulation of the operation of a real thermal drying plant were analysed for various families of odorous compounds including ammonia, volatile amines, sulphur compounds, volatile fatty acids, and volatile organic compounds. The evolution of these compounds was monitored during 4 temperature phases. The concentrations of the chemicals identified were then compared to their highest odour threshold concentration reported in the literature in order to assess whether they contributed to the samples global odour. Compounds confirmed as contributing to dried sludge odours were used to build a comprehensive odour wheel. A sludge drying odour wheel was completed with representative and odorous compounds associated with it. The classification of dried sludge odours has been tested at an operating sludge drying plant.