Advances in membrane operations for water purification and biophenols recovery/valorization from OMWWs Fabio Bazzarelli, Emma Piacentini, Teresa Poerio n , Rosalinda Mazzei n , Alfredo Cassano, Lidietta Giorno Institute on Membrane Technology, ITM-CNR, c/o University of Calabria via Pietro Bucci, 17/C, 87036 Rende, CS, Italy article info Article history: Received 29 July 2015 Received in revised form 17 September 2015 Accepted 19 September 2015 Available online 25 September 2015 Keywords: Olive mill wastewaters Microfiltration Nanofiltration Osmotic distillation Membrane emulsification abstract Recovery of biomolecules from waste represents one of the most important challenges for sustainable resource exploitation. An innovative process design for water recovery and polyphenols encapsulation from olive mill wastewaters (OMWWs) has been investigated combining conventional pressure-driven processes (mi- crofiltration (MF) and nanofiltration (NF)) and relatively new membrane operations (osmotic distillation (OD) and membrane emulsification (ME)). After the removal of suspended solids by an acidification/MF step, OMWWs were processed by NF in order to obtain water from the permeate side and a concentrated polyphenolic solution from the re- tentate side. The NF retentate was dewatered by OD and the concentrated polyphenolic stream was encapsulated in a water-in-oil emulsion by ME. The integrated membrane system resulted efficient in all the operation units. Indeed, relatively high fluxes, with respect to literature data, were obtained in both MF and NF steps (60 and 7 L/m 2 h, re- spectively); in addition high polyphenols rejections (%) were measured for the NF membrane. The concentration of the NF retentate by OD produced an enriched fraction of low molecular weight poly- phenols according to a concentration factor of 7. This fraction is formulated by the ME process for the production of a W/O emulsion with an encapsulation efficiency of 90%. According to the process mass balance, related to the treatment of 1000 L of OMWWs, 1463 g of phenolic compounds (85% of the initial phenolic content) and 800 L (80% of the initial volume) of pur- ified water can be recovered, respectively. & 2015 Elsevier B.V. All rights reserved. 1. Introduction Resource valorisation from waste represents one of the most important challenges for sustainable industrial processes. Limited resources and increasing interest in the use of bioactive com- pounds play an important role in the development of sustainable waste management practices. Several physical, chemical and bio- technological approaches, have been attempted to valorise OMWWs [1] resulting in an environment protection with zero discharge. Membrane processes such as ultrafiltration (UF) and nanofil- tration (NF) have been successfully used for over three decades in food and beverage industries for the treatment of several fluids and agricultural wastewaters [2]. Interesting applications have been developed for the separation, concentration and recovery of high-added value compounds, including pectin and polyphenols, from agro-food byproducts [3,4]. Possibility to operate at room temperature, small area-re- quirement, no phase change and chemical additive use, low in- vestment and maintenance costs, high efficiency and low specific energy consumption are key advantages of membrane technology over conventional separation processes in many wastewater treatment processes [5]. The combination of different pressure-driven membrane pro- cesses for the recovery of polyphenols from OMWs has been lar- gely investigated [6–11]. Integrated systems in which membrane operations have been combined with other separation techniques such as supercritical fluid extraction [12] and chromatographic separations have been also proposed [13] for the recovery of an- tioxidants from OMWWs. By analysing patent publications in this field, Takaç and Karakaya [14] concluded that the future direction of the processes for the recovery of antioxidant compounds from Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/memsci Journal of Membrane Science http://dx.doi.org/10.1016/j.memsci.2015.09.049 0376-7388/& 2015 Elsevier B.V. All rights reserved. n Corresponding authors. Tel.: þ39 0984 492051; fax: þ39 0984 402103. E-mail addresses: t.poerio@itm.cnr.it (T. Poerio), r.mazzei@itm.cnr.it (R. Mazzei). Journal of Membrane Science 497 (2016) 402–409