Olive Oil Wastewater Made to be a Bioethanol Resource

Olive oil mill wastewater is the effluent after olive oil extraction, and is highly polluting because of its high organic matter content. Generally, wastewater with high organic matter content can be treated by conventional biological wastewater treatment or can be utilized as fermentation raw material for the production of value added microbial products. However, this olive oil wastewater also contains high concentrations of phenolic compounds which inhibit microbial activity. This makes biological treatment or microbial fermentation difficult.

Recently, scientists from the Department of Biotechnology and Biological Sciences, Hashemite University, Jordan, reported a way to remove these inhibitory phenolic compounds by fungal treatment, using the fungus Pleurotus sajorcaju. With this treatment, the wastewater is made more amenable to further microbiological processing. Up to a 68% reduction in phenolic compounds was achieved under the best conditions studied. The researchers also showed that the wastewater can be utilized for ethanol fermentation after fungal treatment. Despite the incomplete removal of phenolics after treatment, the wastewater could be effectively utilized by yeasts to produce ethanol at a concentration of 14.2 g/L in 48 hours. The results are published online (5 October 2007) by the American Chemical Society (URL above).