The use of olive mill waste to promote phytoremediation

Olive oil industry generates large amounts of olive mill waste (OMW) materials that generally imply serious environmental concern regarding their storage and management. An interesting and sustainable alternative to conventional waste treatments is their use as amendments in the reclamation of trace elements (TEs) contaminated soils through phytotechnologies. These techniques aim to reduce in situ the toxicity and the dissemination of contaminants, and to restore soil capacity to function as a self-sustaining ecosystem. For that purpose, the addition of soil amendments is often necessary to improve soil fertility and facilitate plant establishment. This chapter reviews the use of the different olive mill by-products in phytoremediation strategies for TEs contaminated soils. The effects of fresh versus processed wastes (compost and biochar) on soil TE solubility and availability, plant development and biological indicators of soil recovery have been examined as key aspects of the reclamation process. Both the potential benefits and the limitations or negative effects that their utilization may pose are pointed out.