Valutazione di un nuovo metodo di compostaggio on farm dei reflui dei frantoi oleari

This paper deals with a new static composting procedure carried out in gas-permeable polyethylene bags (1 m3), aiming at bioremediation of olive mill waste (OMW). OMW (72% w/w) was thoroughly mixed with hygroscopic additives, such as waste wool and straw, to avoid leachate. Temperature and oxygen values measured during composting, showed patterns similar to those reported in classic aerated composting systems. Static composting resulted in a drastic organic matter degradation (48%), an apparent nitrogen increase (N > 3%), with a C:N value close to 10 at the end of process. The compost also showed low polyphenols (0,1 mg g-1) associated to high humic carbon content (12,9 %). Dynamic and static respirometric tests stated high biological stability of the end compost product. The use of bags permitted to avoid any artificial aeration and periodic watering of OMW mixture. In terms of the main chemical physical parameter changes of compost, the innovative system shows to be comparable to conventional composting procedures and leads to the preparation of mature compost, satisfying the standard requirements set by regulators.