(176ak) Valorization of the Waste Streams from the Steam Distillation of Essential Oils, Using Nanomembrane Separation.

The valorization of the wastes in various sectors of the economy, is a strategic direction in the scientific research due to the projections for a sustainable population growth of up to 9 billion people in 2050 and the need for reciprocal increase in food and energy production without adversely affecting the environment. While the primary processing of medicinal and aromatic plants increases the value of raw materials by only 1 to 5%, the selective extraction of valuable substances from them by different extraction methods, aiming at their use in variety of products, adds up to 10-15% [1]. In the case of complex utilization of plant material, the percentage would be even higher, which would increase the attractiveness of this sector and promote sustainable extraction of raw materials in accordance with current environmental standards. Crude and refined plant extracts rich in phenolic compounds are increasingly applied as natural colorants, antioxidants, preservatives and nutritional supplements. The steam distillation remains a major technology, ensuring a high and sustainable quality of the extracted oils [2] and is exclusively used for the production of essential oils from aromatic plants in Bulgaria, which is a world leading producer of Lavender essential oil.

In the present report will be discussed the benefits and the challenges on the application of nanofiltration to fractionate hydrosols, residual waters, and biologically active extracts from spent plant material from the steam and hydrodistillation of essential oil plants. Aromatic plants are sources of polyphenolic compounds with diverse biological activity and also essential oil components. The molecular structures of polyphenolic compounds, containing both hydrophobic parts and hydrophilic functional groups, as well as the possibility for the appearance of stable emulsions are prerequisites for adverse interactions with the polymeric membranes. All these aspects are illustrated with experimental evidences collected by experiments on nanofiltration of residual waters from industrial scale hydrodistilladion of Rosa Damascena petals and hydrosols from the laboratory hydrodistillation of Cloves. Particular attention was drawn on the isolation of biologically active polyphenolic fraction rich in rosmarinic acid from spent plant material after the industrial steam distillation of Lavender essential oil. The solvent extraction of rosmarinic acid from the plant material was optimized. The resulting diluted extract was concentrated at laboratory scale, using a commercially available thin film composite reverse osmosis membrane. The concentrate was subjected to cristallisation or thermal evaporation, in order to obtain the rosmarinic acid in a dry form. A model of a hybrid technology for valorization of the spent Lavender material has been developed in the environment of Aspen Plus process simulation software. The unit operation for a spiral-wound membrane module has been implemented via the OSN Designer software tool [3]. All other unit operation were available in Aspen Plus unit operations library. The model parameters were obtained from the laboratory scale experiments. The model was used to optimize the material and energy streams in the proposed technological diagram and to evaluate its economical viability.

Acknowledgments

This study is funded by the European Union - NextGenerationEU, through the National Recovery and Resilience Plan of the Republic of Bulgaria, project No BG-RRP-2.004-0002, "BiOrgaMCT" and the Bulgarian National Science Fund (contract KP-06-H37/14).

References

[1] http://herbvaluebg.org/

[2] Galanakis, C.M. Food Waste Recovery: Processing Technologies and Industrial Techniques, Elsevier Inc., 2015.

[3] Peshev D.; Livingston A. Chem. Eng. Sci. 2013, 104, 975-987.