Assessment of the Antimicrobial and Fertilizing Activity of Table Olive Concentrated Waste Streams During Their Shelf Life

Table olive wastewaters represent a big problem for factories not yet solved. Some partial solutions are the purification, the reuse or the generation of a smaller volume of these liquids. The purpose of this study was to investigate the possibility of obtaining a concentrate that can be stable over time and that has a biofertilizing capacity on tomato (Solanum lycopersicum L.) plants. In this study, washing waters from Spanish style green and storage liquids from black ripe olive processing were vacuum concentrated up to 10, 13 and 17 times so that they reached total sugar content of up to 700 mmol L−1, 925 mmol L−1 and 1200 mmol L−1 respectively. Interestingly, the evaporation achieved to retain most of the phenolic compounds that ranged from 18 mmol L−1 in the fresh solution to 140 mmol L−1 in the solution concentrated 10 times. Moreover, these concentrates showed in vitro antimicrobial activity against the bacteria Erwinia amylovora and Pseudomonas syringae, and the Oomycota Phytophthora sp. In addition, they increased the strength and cumulative yield of the tomato plants cultivated under greenhouse conditions, even after 12 months of storage at room temperature. It has been demonstrated that it is possible to reduce the large volume of the wastewaters of the table olive industry, and the concentrates have potential application for agricultural uses, even after 1 year of storage, thereby contributing to a more environmentally sustainable industry. Graphical Abstract