Use of clinoptilolite to improve and protect soil quality from the disposal of olive oil mills wastes

In the framework of LIFE07 ENV/GR/000280 Project “Strategies to improve and protect soil quality from the disposal of olive oil mills wastes in the Mediterranean-PROSODOL”, a laboratory experiment was conducted in order to investigate to which extent the natural zeolite clinoptilolite is capable of limiting environmental degradation caused by the uncontrolled disposal of olive oil mills wastes (OOMW). Clinoptilolite was added in various ratios (from 0% up to 30% w/w) to soil samples, which were collected from four OOMW disposal sites (from both the interior of the disposal ponds and the surroundings) located in a pilot Municipality in Rethymno, Crete, Greece. Water soluble K, Ca, Mg, Mn, Zn, Fe, Cu, polyphenols, NO3−, Cl−, SO42− and PO43− were measured in leachates after equilibration of the soil samples with clinoptilolite It was observed that water soluble K, NO3−, Cl−, SO42− and polyphenols were decreased with an increase in zeolite percentage; Ca leaching was slightly increased or remained nearly constant; Mg leaching remained constant or increased, especially for pond soils; and PO43− leaching was very low. Although the soil samples' content in available Mn, Cu, Zn, Fe was high, the metals were not detected in the leachates.