Department of Chemical and Nuclear Engineering, Polytechnic University of Valencia, Camino de Vera, s/n, 46022 Valencia, Spain.
Water Res. 2010 Jul;44(13):3883-92. doi: 10.1016/j.watres.2010.05.005.
The purpose of this work was to analyse the potentialities of an integrated membrane system for the recovery, purification and concentration of polyphenols from olive mill wastewater (OMW). The proposed system included some well-known membrane operations such as microfiltration (MF) and nanofiltration (NF), as well as others not yet investigated for this specific application, such as osmotic distillation (OD) and vacuum membrane distillation (VMD). The OMW was directly submitted to a MF operation without preliminary centrifugation. This step allowed to achieve a 91% and 26% reduction of suspended solids and total organic carbon (TOC), respectively. Moreover, 78% of the initial content of polyphenols was recovered in the permeate stream. The MF permeate was then submitted to a NF treatment. Almost all polyphenols were recovered in the produced permeate solution, while TOC was reduced from 15 g/L to 5.6 g/L. A concentrated solution enriched in polyphenols was obtained by treating the NF permeate by OD. In particular, a solution containing about 0.5 g/L of free low molecular weight polyphenols, with hydroxytyrosol representing 56% of the total, was produced by using a calcium chloride dihydrate solution as brine. The obtained solution is of interest for preparing formulations to be used in food, cosmetic and pharmaceutical industry. Besides the OD process, VMD was applied as another way for concentrating the NF permeate and the performance of both processes was compared in terms of evaporation fluxes.
本工作旨在分析集成膜系统从橄榄厂废水（OMW）中回收、纯化和浓缩多酚的潜力。所提出的系统包括一些众所周知的膜操作，如微滤（MF）和纳滤（NF），以及其他尚未针对此特定应用进行研究的操作，如渗透蒸馏（OD）和真空膜蒸馏（VMD）。OMW 未经预先离心直接进行 MF 操作。这一步骤可分别将悬浮固体和总有机碳（TOC）减少 91%和 26%。此外，多酚的初始含量中有 78%在渗透物中回收。然后将 MF 渗透物进行 NF 处理。几乎所有的多酚都在产生的渗透物溶液中回收，而 TOC 从 15g/L 降低至 5.6g/L。通过对 NF 渗透物进行 OD 处理可获得富含多酚的浓缩溶液。特别是，使用二水氯化钙溶液作为盐水，可生产出一种含有约 0.5g/L 游离低分子量多酚的溶液，其中羟基酪醇占总多酚的 56%。所得溶液可用于制备用于食品、化妆品和制药行业的制剂。除了 OD 过程之外，还应用 VMD 作为浓缩 NF 渗透物的另一种方法，并比较了这两种方法在蒸发通量方面的性能。
