Olive Mill Pomace Treatment: Composting as Organic Fertilizer
In modern olive mills, the most common method for extracting olive oil from the olive paste is two-phase decanter. Because the two-phase extraction system is less complicated, consumes less energy and yields higher quality olive oil, there is approximately 90% olive mills in Spain using this technology. The modified extraction system uses no process waster and delivers only two streams: olive oil and a single waste- a combination of olive husk and olive mill waste water- a very wet olive cake, which is called “Olive Mill Pomace”
Olive mill pomace (OMP) is a main by-product of the olive oil extraction industry.
Ingredients of OMP
The olive pomace is composed of fruit matter (olive skins, flesh, seeds and stone fragments), and of different amount of vegetation and process water increasing the moisture content up to 50-70%.
Features of OMP
Olive wet pomace (also know as olive wet cake, olive wet husk) is a semi-solid waste which has a strong odor and doughy texture. This residue is characterized by slightly acidic pH, high organic matter concentration (mainly of lignocellu-loseic origin) and the presence of valuable nutrients, especially K.
Amount of OMP
In many Mediterranean countries, the olive oil industrial sector generates a great amount of olive mill waste in a short period every year. In Andalusia, Spain, there are about four million tons of olive mill pomace being produced annually. A major environmental problem in the Mediterranean countries is the disposal and/or treatment of the large quantities of OMW and olive cake produced during olive oil processing.