OLIVE OIL WASTE GETS SUSTAINABLE

Image by ValentynVolkov Getty Images

When olive oil is produced commercially, olives are crushed and mixed with water in mills. The oil is then separated out and saved, while the leftover water and solid residue are wastefully discarded. In order to combat this, scientists have devised a process of converting olive mill wastewater into biofuel, fertiliser and clean water.

As things currently stand, there's no good way of disposing of the wastewater. Dumping it in waterways pollutes them while pumping it directly onto farmland damages the soil and reduces crop yields.

Image Straniero Olive Oil

That's why a team led by Mejdi Jeguirim of France's Mulhouse Institute of Materials Science has taken a different approach. The scientists started by mixing the wastewater with cypress sawdust, which is another waste product that's common in the Mediterranean, where 97 percent of the world's olive oil is produced.

That mixture was rapidly dried and the water was collected as it evaporated – this water is clean and can be used to irrigate crops. The remaining dried material was then subjected to pyrolysis, which is a process wherein organic material is exposed to high temperatures in the absence of oxygen. This caused it to decompose into combustible gas and charcoal pellets.

That gas was collected and condensed into bio-oil, which could ultimately be used as a heat source for the drying and pyrolysis processes. The charcoal, meanwhile – which contains high amounts of nutrients such as potassium, phosphorus and nitrogen – was gathered and used as a crop fertiliser. In field tests, it was found that the pellets “significantly improved plant growth”.

Image by smoxx Depositphotos

This research is just the beginning of a process that could reveal even more fruitful results. 

Via New Atlas