Department seminar - Christakis Paraskeva
In the present work, two different activities of the Laboratory are presented on issues related to the consolidation of loose materials and to the treatment of agro-industrial wastewaters.
The first part of the presentation is related to the theoretical and experimental study of the in-situ precipitation and growth of sparingly insoluble salts on the surfaces of grains of a porous media in applications such as: consolidation of loose rock formations in oil well reservoirs, waterproofing of concrete constructions, and protection of cultivated soils from water erosion, etc. Results of the simulation of the introduction of the solutions into the porous materials, of the in situ mixing of the salt solutions, of the precipitation of the desired salt and of the growth of crystals on the surface of the grain surfaces, are illustrated. Results for crystal precipitation and crystal growth are also depicted in porous materials in the presence of dissolved organic compounds such as ethylene glycol or in the presence of insoluble organic compounds, such as dodecane under different flow conditions and geometries of the porous material.
The second part of the presentation will include a summary of the work done at both laboratory and pilot level for the processing of solid wastes and wastewaters from agricultural activities. More specifically, examples will be presented for the treatment of liquid and solid wastes produced in olive oil mills and winery, (two and three-phase olive oil mill wastes, olive leaves, altered wine and grape marc) using membrane filtration (Ultrafiltration, Nanofiltration and Reverse Osmosis) and other physicochemical techniques, such as adsorption on ion exchange resins and vacuum evaporation, freeze-drying. Results have shown that 70% of the total volume of wastewater treated by the membrane units is clean water suitable for irrigation while membrane concentrates have been further processed to isolate phenolic substances in high purity and for their exploitation in the food and pharmaceutical industries. These products have a high added value and further refining of them to higher purity products (> 90%) is part of the current laboratory's work. This current work has, mainly, focused on investigating the recovery of phenolic compounds at high levels of purity from liquid agglomerates of agricultural waste/byproducts, emphasizing the application of combination physicochemical membrane filtration and crystallization processes.