A report put together by nine scientists shows that olive mill wastewater can be converted from a pollutant into sustainable products for practical use.
The harmful by-products that come from the production of olive oil used in kitchens across the world could instead be used to irrigate agriculture, fertilise crops and power machinery, after a group of scientists appear to have developed a method to stabilise them. The process by which olive oil is produced requires the fruit to be crushed and mixed with water in mills, in turn producing dirty water and solid particles that need to be discarded. Perhaps surprisingly for a by-product of water and olive, the waste material is can potentially contaminate drinking water and harm aquatic life, making it difficult to dispose of.
The Mediterranean region produces 97% of the world’s olive oil, which is a standard ingredient in a huge number of popular cuisines, and generates eight million gallons of waste water. In an attempt to safely dispose of the waste products, researchers have in the past tried burning the wastewater that has been mixed with solid waste from the olive mills or waste wood. However, current methods of doing this can be expensive and produce excessive quantities of air pollution.
The latest attempt to make olive oil production sustainable has been revealed in a study that appears in ACS Sustainable Chemistry & Engineering, where a report put together by nine scientists shows that olive mill wastewater can be converted from a pollutant into sustainable products for practical use.
As the first port of call in the scientists’ drive to improve the production of the kitchen staple, olive oil wastewater was combined into another common Mediterranean waste product, cypress sawdust. By then rapidly drying this mixture and collecting the evaporated water, the scientists claim they could safely use it to irrigate crops.
In creating a sustainable fuel that can be used to power a range of machinery, the scientists subjected the sawdust mixture to pyrolysis, a process in which organic material is exposed to high temperatures in the absence of oxygen. Without oxygen, the material doesn’t combust, but it does thermally decompose into combustible gases and charcoal.
Finally, to produce a completely sustainable fertiliser, the scientists explained in the report how they collected the charcoal pellets, which are packed full of potassium, phosphorus, nitrogen and other nutrients, then using them to fertilise crops. The researchers found that after five weeks these pellets significantly improved plant growth, including larger leaves, compared to vegetation grown without them.
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