 Incinerator sludge ash is becoming more popular as a secondary resource due to its large production and relatively stable composition. It contains valuable elements such as metals and minerals which can be recovered through various methods including acidic and alkaline leaching, chelating and sequential leaching. However, these methods have limited effectiveness and require further development. Microbial approaches have been explored but are not widely used due to their potential advantages over other methods. Additionally, the mineral and chemical composition of incinerator sludge ash varies between plants, making it necessary to develop an individual approach. This article was authored by Monica Casina and Kinga Jaros.