Home Management Agricultural wastes : characteristics, types, and management
Non-energy Use of Olive Stones
Non-energy uses for olive stones have been reported in literature. Some of the most important are described below.
The possibility of using olive stones as adsorbent, either directly  or transforming them into activated carbon [25, 26, 27, 28], has been investigated. Non-activated endocarps, finely divided, allow to separate heavy metals in wastewater. For example, in literature it can be found recoveries higher than 80% for Cr3+ and Cr6+ , approximately 90% for cadmium ions  and above 70% for Fe3+ . In addition, olive stones have been reported as adsorbent for drin pesticides .
Source of Natural Antioxidants
The two-phase pomace is interesting to produce some natural compounds with high antioxidant power, such as hydroxytyrosol or 3,4-dihydroxyphenylglycol . The treatment of olive endocarps with the so-called technique 'steam explosion' (operating at 200-235°C maintained for 2 minutes) allows to retrieve large amounts of hydroxytyrosol in the liquid hydrolysate , which has led to a patent currently under exploitation (Ref OEPM Spanish Patent. P200100346). Meanwhile, Cuevas et al. (2007) verified that when increasing the operational temperature from 190 to 225°C in the hot water treatment of olive stones, the amount of hydroxytyrosol, vanillin and syringic acid was increased by 48, 151 and 369%, respectively .
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