Juan Miguel Romero-García

Biorefinery based on olive biomass. state of the art and future trends.

With currently more than nine million hectares, olive tree cultivation has spread worldwide, table olives and olive oil as the main products. Moreover, a number of by-products and residues derived from both tree cultivation and the process of industrial olive oil production, most having no practical applications, are obtained yearly. This paper reviews the research regarding these by-products, namely biomass from olive tree pruning, olive stones, olive pomace and wastewaters obtained from the process of olive oil production. Furthermore, a wide range of compounds has been identified and can be produced using a broad definition of the term biorefinery based on olive tree biomass. As an example, this paper reviews ethanol production as one of the main proposed applications, as well as research on other value-added products. Finally, this paper also assesses recent technological advances, future perspectives and challenges in each stage of the process.

Obtaining sugars and natural antioxidants from olive leaves by steam-explosion.

In this work, steam-explosion treatment was evaluated as a procedure to recover sugars and natural antioxidants from olive tree leaves. The treatment was carried out following a Box-Behnken experimental design, with three factors, temperature (180-220°C), process time (2-10min) and milling time (0-15s). Response surface methodology showed that temperature was the most influential factor, followed by process time, while the best results were achieved with whole leaves. The operational conditions for simultaneously maximizing the sugars and natural antioxidants recoveries resulted to be 180°C, 8.3min and whole leaf; under these conditions 18.39g and 1950mg were obtained from 100g dry olive leaves, respectively. This is equivalent to 70% recovery of the initial sugars present in olive leaves, with a very low formation of inhibitory compounds and an important amount of natural products with antioxidant capacity such as oleuropein, hydroxytyrosol and flavonoids.

Environmental Assessment of Biorefineries

The development of the biorefinery concept is based on the techno-economic feasibility of the proposed process considering raw materials, process options, mass and energy integration, market constraints, etc. Nevertheless, along with all these considerations, the environmental assessment must be taken into account at the same time, and concepts like sustainability, land uses, environmental impacts, and other related issues must be included in the biorefinery design since the first moment. This work summarizes the main methodologies and aspects concerning the environmental assessment of biorefineries. Different case studies covering a wide range of raw materials and products are also presented.