Biodegradation of olive husk mixed with other agricultural wastes

In this study, the evolution of the most important parameters (temperature, pH, electrical conductivity, total organic carbon, total nitrogen, and C/N ratio) describing the composting process of olive oil husk with other organic wastes was investigated. Four windrows for obtaining two mixed wastes composts (MWCs) and two green wastes composts (GWCs) were prepared.All the raw materials used showed appropriate physical and chemical properties for composting process. The total organic carbon values of the final composts were suitable for agricultural purpose and in particular two of them (one MWC and one GWC) showed an increase of 47.6% and 40.3% in respect to the minimum levels established by the Italian legislation. After the biodegradation the C/N ratio could be considered satisfying for ready-to-use compost in three of the four windrows. The Ni and Pb concentrations did not overcome the Italian law limits in all windrows, while the Zn content was higher than the limit value only in two windrows (one of both MWC and GWC composts).The findings highlighted that among the four composting processes, the best general results were found for one of the two GWCs produced.