Nanofiltration of Cork Wastewaters and Their Possible Use in Leather Industry as Tanning Agents
V. Geraldes1, M. Minhalma2, M. N. de Pinho1, A. Anil3, H. Ozgunay3, B. O. Bitlisli3, O. Sari3
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1Department of Chemical and Biological Engineering, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal
2Department of Chemical Engineering, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emídio Navarro 1, 1959-007 Lisbon, Portugal
3Leather Engineering Department, Engineering Faculty, Ege University, 35100 Izmir, Turkey
Pol. J. Environ. Stud. 2009;18(3):353–357
Cork processing wastewater is a very complex mixture of vegetal extracts and has, among other natural compounds, a very high content of phenolic/tannic colloidal matter that is responsible for severe environmental problems. In the present work, the concentration of this wastewater by nanofiltration was investigated with the aim of producing a cork tannin concentrate to be utilized in tanning. Permeation results showed that the permeate fluxes are controlled by both osmotic pressure and fouling/gel layer phenomena, leading to a rapid decrease of permeate fluxes with the concentration factor. The rejection coefficients to organic matter were higher than 95%, indicating that nanofiltration has a very good ability to concentrate the tannins and produce a permeate stream depleted from organic matter. The cork tannin concentrate obtained by nanofiltration and evaporation had total solids concentration of 34.8 g/l. The skins tanned by this concentrate were effectively converted to leather with a shrinking temperature of 71oC.