Utilization of carbonized sewage sludge as a mineral fertilizer: environmental and agronomic aspects

Abstract

Background and Aim. In the context of the growing need for sustainable agricultural technologies, this study explores the possibility of recycling pyrolyzed sewage sludge as a fertilizer. The aim was to identify the optimal carbonization temperature of sewage sludge to obtain a safe and effective product that promotes plant growth.

Materials and Methods. Arugula microgreens (Eruca sativa) were used as a model due to their rapid response to environmental changes. Soil samples with different carbonized sludge contents (10-30%) processed at temperatures ranging from 350 to 700 °C, were prepared, and six irrigation regimes were applied, including one with potassium humate.

Results. The experimental results showed that sludge carbonized at 700 °C had the most beneficial effect on plant growth: enhanced germination, shoot elongation, and increased yield were observed. These effects are attributed to the detoxification of the material and the preservation o nutrients during thermal treatment.

Conclusion. The study highlights the potential of carbonized sludge as an environmentally friendly alternative to conventional fertilizers and its contribution to the development of a circular economy.