Olive production across the Mediterranean Basin has a long and prestigious past, which today is firmly rooted in the economic, social and cultural life of its inhabitants. Around the region, around eight million hectares are dedicated to olive cultivation producing, all told, some 1,800,000 tons of oil.
The project concentrated on olive oil production processes in Spain, Italy and Greece. To extract olive oil, three different methods are commonly used. The traditional press method is a non-continuous process which provides high purity extra virgin olive oils. The other two techniques are the two- and three-phase decanter centrifuge methods. The three-phase is a continuous process that requires the addition of warm water to improve extraction, as is the two-phase which differs by operating without adding any water. This last is the most innovative technique and produces a semi-solid cake of pressed olive fruits and stones as opposed to the highly polluting wastewater from the three-phase process. This wastewater needs treatment before disposal.
Olive oil waste has always been one of the biggest problems associated with the industry. The environmental devastation, caused by the accidental release of non-treated waste that periodically occurs, bears witness to this. However, recent innovations in extraction technology have resulted in new types of waste, making much of existing waste treatment and recovery obsolete.
Not wasted at all
Nonetheless, this project – consisting of 19 partners from the UK, Spain, Italy, Greece and The Netherlands – aims to develop uses for olive oil waste in five different areas. Using carbon dioxide for supercritical fluid extraction and the chemical compound 1,1,2-tetrafluoroethane for solvent extraction, high value-added components will be extracted. Both processes are at the vanguard of extraction technology and will provide the raw materials for nutritional and pharmaceutical applications, and flavours and oils.
While petrochemical oils are used for domestic and commercial energy, there is no reason not to use other more natural oils for the same purpose. Hence the use of olive oil waste as a low cost renewable energy source will also be targeted. This involves the absorption of spilt oil, which could then be incinerated for energy recovery. It has already been shown that the absorption of oil spills is feasible.
Biosorption is the process of biologically recovering pollutants. Olive oil waste will be tested as an adsorbent of contaminants such as metals and colours from aqueous effluents.
Preliminary studies have shown that the waste adsorbs (i.e. binds) toxic cadmium, copper and lead – a promising early result. Yet another part of the work package will try to break down waste through the use of anaerobic bacteria, leaving it in a less polluting form.
Through this, methane could be produced which could be used as an energy source. In agriculture, waste is often spread on the surface as a fertilizer, returning nutrients to the soil. Olive oil waste will be investigated to see if it can be put to the same use to improve crop yield and quality. Through work conducted so far, the exact chemical and physical properties of olive oil waste has been ascertained. This forms the basis for much of this project’s future work.
In today’s climate of re-use and recycling it is refreshing to see an industry that generates a lot of waste being able to put its waste to good use: a case of changing the age-old saying from waste not, want not, to waste it, want it.