Pelletization of Compost from Different Mixtures with the Addition of Exhausted Extinguishing Powders

Abstract

Today, in Europe, there is still no industrial process to favor the distribution of exhausted extinguishing powders (EEP). Extinguishing powders (EP) are the most common extinguishing agents and are composed of very fine particles (90% is less than 0.250 mm, with at least 40% less than 0.040 mm). Illegal processes of disposal or reuse of EEP are currently taking place throughout Europe. In fact, often maintenance companies illegally dispose of and/or reuse spent extinguishing powders with enormous environmental damage. This is partly due to prohibitive costs, of which a large part is due to transport. The demand for fertilizers is increasing; phosphorus is a key raw material, and a possible solution could be mixing it with compost and other organic biomass and agricultural residues. In general, both compost and EEP powder have a low density and can take up a great deal of storage volume, so thickening this compost would help reduce the required storage capacity. Furthermore, a danger represented by the handling of compost and EEP is the dispersion of dust that can potentially carry pathogens and toxic organic substances which, if inhaled, could cause respiratory problems during distribution and handling. The aim of this study was to produce compost pellets using exhausted EP in different formulations and to observe the quality of different compost pellet products with respect to different factors affecting handling, storage, and distribution. For the first time, the pelletizing of EEP with compost was performed successfully using five different blends, each with different properties. The results showed that qualitative variables could be controlled to optimize production efficiency and improve the quality of the finished product depending on the type of distribution, handling, and storage. The five compost mixes could be applied in different agricultural crops as fertilizer. Furthermore, this use of exhausted EP allows for positive ecological and economic effects, avoiding the disposal costs required by specialized companies.