The European Union (EU)-funded project developed a system to re-use the water used to wash olives, good news for both the environment and olive producers limited by low water levels, said a press release of the European Commission on Tuesday.
Olives are a "superfood" that creates thousands of jobs in the Mediterranean region, but producing table olives or olive oil requires huge amount of water, sometimes a scarcity in hot, dry southern Europe, said the press release.
Data shows that producing 100 kilos of olives requires around 50 liters of water. The ALGATEC II project has found a way to re-use the water used to wash olives, cutting the use of drinking water by 90 percent and removing the wastewater disposal problem.
"We really think this can work," said project coordinator Antonia Lorenzo of Spanish SME BIOAZUL, "growing global demand for olive oil is considerably increasing the use of water in countries where this resource is scarce and moreover, there is significant waste, especially wastewater."
Polyphenols are one of the reasons that olives are so good for us. Naturally present on the skin of olives, research shows these antioxidants may help protect us from disease. But when they are released into the environment in large volumes, such as in olive wash water, they can be harmful.
Olive wash water is traditionally left in large evaporation ponds, but the ponds have a limited capacity, which in turn limits production, and must sometimes be emptied manually.
Meanwhile, the odors and insects that accompany stagnant water are unpleasant for the olive mill's neighbors.
The ALGATEC II approach first involves pumping the wash water to a photobioreactor, where micro-organisms absorb the pollutants.
In winter, when sunlight is lacking, solar panels can be used to heat the water, increasing the organisms' growth to speed up the process.
The effluent then goes through a final "polishing step," where it is passed through two membrane filters that remove any remaining pollutants. What's left can be used as drinking water, or to wash more olives. It can also be discharged safely into sewers while dirty wastewater cannot.
While the solution cannot compete with evaporation ponds on cost, it removes many of the problems associated with the ponds and also allows producers to expand production.
The system can also be tailored to the producer's needs - the final filtering step is not necessary if drinking water is not required.
The additional cost attached to a liter of olive oil would be "almost nothing," said Lorenzo, and the technology is cheaper than current alternatives on the market.
A demonstration plant is up and running at the University of Huelva in Spain, and the five ALGATEC II partners - SMEs from Spain, Italy and Germany - are now working on a business plan to put the technology on the market, said the press release.