Olive Mill Wastewater: treatments and valorisation

Olive mill wastewaters represent a serious environmental problem in Mediterranean countries, as the high concentrations of phenols, lipids and organic acids can have phytotoxic effects. On the other hand, this waste also contains valuable compounds, such as a large amounts of organic matter and a wide range of nutrients that could be recycled. In this chapter, the most interesting physico-chemical and biological processes for the treatment of these effluents are presented. Remediation by means of physical and chemical methods are generally expensive, and they do not often provide complete purification. Indeed, despite the effectiveness of such techniques, few of them have been applied on an industrial basis. Biological processes for the treatment of olive mill wastewaters have seen worldwide applications, and they are considered to be environmentally friendly, reliable and, in most cases, cost effective. Moreover, some biological treatments are effective for the valorisation of this organic waste.