Olive oil production in the Mediterranean basin generates huge amounts of potentially polluting organic waste, namely olive-waste cakes, which urges to be economically and environmentally viable. Among the possible valuations of this residue its use as an organic fertilizer is particularly important for the poor Mediterranean soils. However, because of its composition, the direct use of this waste is impracticable especially in annual crops and must undergo a composting process before being utilized. It was with the objective to follow the difficult composting process of this residue, and the changes of its composition throughout this process, that we developed this study. To this end, after characterizing the residue to be composted and having decided to mix straw as a structuring product in order to facilitate the development of the aerobic biological transformation process, we established a static pile with mechanical stirring and manual humidification, weekly controling the evolution of the composition of the residue during the composting process. The results show the lowering of the C/N and C/P ratios and a significant content decrease in phenols and polyphenols. As a conclusion we state that the process of composting, that we have developed, is valid to transform this residue into organic fertilizer, free of phytotoxicity, rich in humid organic matter and with a considerable macronutrient content that can be used economically and that it is environmentally adequate for the fertilization of agricultural soils
olive-waste cakes, composting, fertilizer, organic, residue
Cite this paper
José Rato Nunes, José Telo Da Gama, João Carvalho, António Lopezpiñeiro, David Peña, Luis Loures. (2019) Two Phases Olive Mil Residue Composting – Chemical Changes During the Process. International Journal of Chemistry and Chemical Engineering Systems, 4, 38-43
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