Use of olive mill wastewater (OMW) to decrease hydrophobicity in sandy soil

This study explores the potential effectiveness of olive mill wastewater (OMW) as an alternative to industrial surfactants in decreasing hydrophobicity in sandy soil. The OMW was obtained from a storage lagoon and characterized by high concentrations of short-chain fatty acids, mainly butyric, propionic and acetic, which contributed approximately to 1/3 of the wastewater organic load. It was applied diluted with freshwater (1:1) in an agricultural field in Greece affected by water repellency at a rate of 4 L/m2. OMW was found to be effective in decreasing soil water repellency, which suggests the potential of OMW to be used as a natural surfactant. The decrease in hydrophobicity was attributed to the fatty-acid related surface-active properties, enabling rapid penetration of OMW into the soil matrix, and the consequent enhancement of soil microbial activity that enables degradation of soil hydrophobic compounds.