SELECTIVE PHENOL REMOVAL MEMBRANES AND VALORIZATION OF OLIVE OIL WASTE STREAMS

Abstract

The present invention discloses stable composite membranes comprising a porous support having one or more thin selective layers coated on a top surface thereof, whereas at least one of said thin selective layers comprises a crosslinked fluorinated silicone polymer, and further wherein the total thickness of said one or more thin selective layers ranges between 0.1 to 10 microns. The use of these membranes in the process of olive oil wastewater treatment and the valorization of polyphenol-rich by-products, are also disclosed.

Claims

1-33. (canceled)

34. A stable composite membrane comprising a porous support having one or more thin selective layers coated on a top surface thereof, whereas at least one of said thin selective layers comprises a crosslinked fluorinated silicone polymer, and further wherein the total thickness of said one or more thin selective layers ranges between 0.1 to 10 microns.

35. The composite membrane of claim 34, wherein the total thickness of said one or more thin selective layers ranges between 1 to 5 microns.

36. The composite membrane of claim 34, wherein one or more of said thin selective layers further comprises at least one polyphenol and/or at least one polymer having one or more aromatic hydroxyl groups.

37. The composite membrane of claim 36, wherein said polyphenol is selected from polyvinyl phenol and/or hydroxy tyrosol.

38. The composite membrane of claim 34 wherein said fluorinated silicone polymer is selected from fluorinated polysiloxanes, fluorinated polysilanes, fluorinated chlorosilanes, fluorinated alkoxysilanes, fluorinated aminosilanes, fluorinated silicone esters, fluorinated polydialkylsiloxanes, and phenyl substituted fluorinated polysiloxanes.

39. The composite membrane of claim 34, wherein said porous support is selected from an ultrafiltration (UF) membrane, a microfiltration membrane (MF) and a non-woven polymer.

40. The composite membrane of claim 34, wherein said one or more thin selective layers further comprises a non-fluorinated silicone polymer.

41. The composite membrane of claim 34, wherein one or more of said thin selective layers further comprises a monophenol.

42. The composite membrane of claim 34, comprising a single thin selective layer.

43. The composite membrane of claim 42, wherein said single thin selective layer comprises Poly-trifluoropropylmethylSiloxane (PTFS) and polyvinyl phenol.

44. The composite membrane of claim 43, further comprising Tyrosol.

45. The composite membrane of claim 34, comprising two selective layers.

46. The composite membrane of claim 45, wherein one of said layers comprises crosslinked Poly-trifluoropropylmethylSiloxane (PTFS) and polyvinyl phenol, and a second of said layers comprises polyvinyl phenol and tyrosol.

47. The composite membrane of claim 34, comprising three selective layers.

48. The composite membrane of claim 47, wherein both a first and a last of said layers comprises a crosslinked Poly-trifluoropropylmethylSiloxane (PTFS), and whereas a second of said layers, in between said first and said last layers, comprises polyvinyl phenol and tyrosol.

49. A process for the preparation of the composite membrane of claim 34, said process comprising a. Preparing a first coating solution comprising a crosslinkable fluorinated silicone polymer, a crosslinking agent, a catalyst and a solvent, and optionally a polyphenol and/or a monophenol; b. contacting said coating solution onto a top surface of a porous support thereby forming a layer onto said support; c. curing said layer for a time ranging from 30 minutes to 4000 minutes and at a temperature ranging from 20 C. to 85 C. to obtain a first stable thin selective layer having a thickness ranging between 0.1 to 10 microns; and d. optionally further preparing one or more additional coating solutions, each comprising one or more of a crosslinkable fluorinated silicone polymer, a fluorinated silicone polymer, a non-fluorinated silicone polymer, a crosslinking agent, a catalyst, a polyphenol, a monophenol, and a solvent; contacting said one or more additional coating solutions with said first thin selective layer, and curing said additional layers, so as to obtain a total thickness of said one or more thin selective layers ranging between 0.1 to 10 microns.

50. The process of claim 49, wherein said crosslinking agent is selected from: organic peroxides, inorganic peroxides, alkoxysilane, and a polysiloxane.

51. A membrane contactor unit, comprising the composite membrane of claim 34, in which the selective side of said membrane faces a feed stream rich in polyphenols whereas the porous side of said membrane is adjacent to a high pH strip solution.

52. A process for obtaining a polyphenol rich concentrate of an olive oil mill wastewater stream, said process comprising: a. Contacting an olive oil mill wastewater stream with an acid, to obtain an acidified olive oil mill wastewater stream at a pH ranging from 2 to 2.5; b. Feeding said acidified olive oil mill wastewater stream into a holding tank, and phase separating from said olive oil mill wastewater: i. a bottom layer stream rich in suspended solids, ii. a top layer stream rich in olive oil iii. a middle layer stream, that is largely devoid of suspended solids and of olive oil; c. Feeding said middle layer stream into an ultrafiltration unit (UF), thereby separating said middle layer stream into a UF permeate and a UF concentrate; d. Feeding said UF permeate into a nanofiltration unit (NF), thereby separating said UF permeate into a NF concentrate rich in polyphenols and a NF permeate largely free of polyphenols; e. Separately feeding each of said UF concentrate and said NF concentrate into a selective side of a membrane contactor unit comprising the composite membrane of claim 1, and circulating said concentrate next to a selective side of said membrane, further whereas a high pH strip solution is circulated next to a porous side of said membrane, to obtain a polyphenol rich permeate stream at the porous side of the contactor membrane unit; f. passing said polyphenol rich permeate stream through a second nanofiltration unit (NF2), thereby obtaining a concentrate which is a polyphenol rich product, and a caustic solution permeate.

53. The process of claim 52, wherein said polyphenol rich product comprises at least 5% of phenols and/or polyphenols.

54. The process of claim 52, further comprising purifying said polyphenol rich product of NF2.

55. The process of claim 52, further comprising passing said first NF permeate through a biological treatment unit, to obtain an irrigation-adequate stream having a chemical oxygen demand (COD) lower than 300 mg/L.

56. The process of claim 52, further comprising recycling said caustic solution permeate into said porous side of said membrane contactor unit, thereby stripping out additional polyphenol.

Description

EXPERIMENTAL SECTION

[0187] Reference is now made to the following examples, which together with the above descriptions, illustrate the invention in a non limiting fashion.

Materials

[0188] NADIR UF membranes having a Molecular Weight Cutoff (MWCO) of 50 kDA, were purchased from Microdyn-Nadir GmbH.

[0189] NF membrane, NF-270, was purchased from Dow Liquid separation systems and the membrane DK-5 was purchased from General Electric.

[0190] RO membranes used in concentration runs, RO-1 and RO-2 were Dow-Filmtec SW30-4040 four-inch spiral wound seawater reverse osmosis elements purchased from Dow Liquid separations.

[0191] Polypropylene (PP) non-woven membrane was purchased from AWA.

[0192] Polydimethylsiloxane (PDMS) membrane was prepared as described below.

[0193] PolyTriFluoropropylmethylSiloxane (PTFS) solution was purchased from Gelest.

[0194] Poly (4-vinylphenol) (P4VP, also known as PVP or polystyrene hydroxyl) was purchased from Sigma Aldrich.

[0195] Tetra ethyl ortho silicate (TEOS, crosslinker) was purchased from Sigma Aldrich.

[0196] Dibutyltin dilaurate (catalyst) was purchased from Sigma Aldrich.

[0197] All other chemicals were purchased from Sigma/Aldrich.

General Synthesis Methods

Membrane Manufacturing

[0198] The area of double (folded) support is 2(10 cm12 cm)=240 cm2.

[0199] Each support was washed overnight in 0.5% NaOH and then rinsed with DI water. Before use, the supports were placed in isopropanol to take out the water.

[0200] Before coating, the pores of supports are filled with a non crosslinked polysiloxane (MW 4200) which serves as a pore protector, to prevent compaction of the UF membrane during heating.

[0201] The coating solution was poured in a homemade metal bath, and the support was coated by standard dipping methods. After dipping, the coated support was drained at room temperature for 72 hours in a hood.

[0202] For the preparation of multilayered membranes, after each layer the coated support was drained in a hood for 30 minutes and cured in oven for 1 hour at 50 C. After curing the support was cooled for 15 minutes at room temperature.

Coating Solution Preparation

[0203] Each of the components: Fluorinated polysiloxane Polytrifluoropropylmethylsiloxane (PTFS), Poly (4-vinylphenol) (PV4P), Tetraethylortosilicate, Dibutyltin dilaurate and Tyrosol, were weighed separately in small glasses with use of plastic pipettes. The solvent (THF) was added to obtain the desired concentration of each component.

[0204] Each component of the coating solution was dissolved separately at gentle mixing using a magnet stirrer at room temperature for 30 minutes.

[0205] The final coating solution was prepared as a mixture of the prescribed components in a closed glass container for 1 hour at room temperature.

[0206] Below are details for preparation of the membranes which include the preferable membrane formulations: #80 and #81

[0207] For membranes manufacturing the following solutions in large volumes:

[0208] A) PTFS 1% solution in THF: 1 g PTFS was dissolved in 99 ml of THF until full dissolution.

[0209] B) PV4P 1% solution in THF: 1 g PV4P was dissolved in 99 ml of THF until full dissolution.

[0210] C) 1 g dibutiltin dilaurate in 99 ml THF.

[0211] D) 1 ml TEOS in 99 ml THF.

[0212] E) 10 gr Tyrosol in 90 ml THF.

[0213] F) 0.5 g PTFS is dissolved in 99.5 ml THF.

[0214] G) 0.5 g PV4P is dissolved in 99.5 ml THF.

[0215] H) 5 gr Tyrosol is dissolved in 95 ml THF.

[0216] J) 0.5 ml dibutiltin dilaurate is dissolved in 99.5 ml THF.

[0217] K) 0.5 ml TEOS in 99.5 ml THF.

[0218] For each membrane, the various solutions of all the components were mixed, and the solvent (THF) was added to obtain a 10% solution for coating.

Novel Membrane Contactor Unit Procedure

[0219] A system of membrane contactor units was designed and assembled to characterize the mass transfer properties of the membranes. These contactors were joined in series on the feed side so that all membranes in a given experiment were exposed to the same feed, and the contactors were arranged in parallel on the strip side so that there was a separate strip solution being cycled past each membrane contactor. This arrangement allowed either several different membranes to be tested, or replicates of the same membranes under identical operating conditions. The membrane contactor units were manufactured by use of 3D printer and Fused Deposition Modeling (FDM) Technology and had channel heights of approximately 2 mm and a membrane area of 21 cm.sup.2 for each contactor.

[0220] After manufacturing, the tested membranes were rinsed in deionized water for 30 minutes and after this were placed in membrane contactor units with the selective layer facing to feed and were assembled with use of metal mounting hardware.

[0221] The pH of the stripping solution on the permeate side was manually maintained constant at pH=13 by adding NaOH solution. The samples were withdrawn from the feed and permeate phases at given time interval and sent for Total phenol and HPLC determination.

[0222] The characteristics and experimental conditions are provided below:

TABLE-US-00001 Parameter Value Feed circulation flow rate 200 ml/min Stripping solution circulation 200 ml/min flow rate Feed concentration 2-9 gr/L Stripping solution (NaOH at pH 1 gr/L ~13) Membrane materials Polydimethylsiloxane, PolyTriFluoropropylmethylSiloxane Polyvinyl phenol tetraethyl orthosilicate dibutyltin dilaurate Membrane area 3 cm 7 cm = 21 cm.sup.2 Volume of the feed tank 1 liter Volume of the each permeate 0.5 liter (stripping) solution tank Temperature in the solutions 25-50 C. pH in the permeate (stripping) 11-13 solution pH in the feed 2-2.5

Methods and Analysis

[0223] Percentages are weight percentages (wt), all fractions are by weight and all temperatures are in C., unless otherwise indicated.

[0224] Membrane performance was tested with respect to Mass flux (MF, in mg/m.sup.2*sec), Overall mass transfer coefficient (OMTC, in m/sec), stability and selectivity with respect to different solutes found in the feed stream.

The equation connecting OMTC to Mass flux was as follows:

OMTC=MF/(Average Feed Concentration of Polyphenol).

[0225] The following operating conditions were used: The feed was kept at pH 1-3 with HCl or H.sub.2SO.sub.4 and the permeate stream was kept at pH 11-13 with NaOH. If dialysis cells were used, then only mechanical stirring was employed for fixed volumes of feed and basic extractant solution located on opposite sides of the membranes. In the flow cells, feed was passed over the selective coated side of the membrane and the high pH strip solution was recycled over the backside of the composite membranes and served as the receiving phase for polyphenols and other organics which permeated the membrane from the feed solution.

Membranes Characterization in Dialysis Cell

[0226] The test was made at average temperature of 25 C. The testing was carried out by placing the tested membrane in a dialysis cell. The tested sample covered the cell orifice with diameter 30 mm. Sample area was 706.5=.sup.2. Each compartment volume was 50 ml.

[0227] The feed compartment was filled with synthetic mixtures of polyphenols. The pH of the feed solution was adjusted to pH=2 by H.sub.2SO.sub.4. The permeate compartment was filled by distilled water with pH=13 adjusted by NaOH.

[0228] At regular time intervals, samples from the permeate and from the feed sides of the cell were taken out and their Total phenol or HPL were analyzed. pH was not adjusted after each sample was taken due to its minimal change both in feed and in permeate compartments during 6 hours.

Experimental Results

Example 1: Preparation of Various PTFS-Coated Composite UF Membranes

[0229] An example of the membrane preparation method for one embodiment is as follows:

[0230] Poly (4-vinylphenol) (PV4P) was mixed at 40 C. for 1 hour with different amounts (see Table 1 for quantities) of tetra ethyl ortho silicate (TEOS, crosslinker). Then, the obtained mixture was added to a PolyTriFluoropropylmethylSiloxane (PTFS) solution with dibutyltin dilaurate catalyst (see Table 1 for quantities), mixed carefully again for 1 hour at room temperature and used immediately for the preparation of the composite membranes.

[0231] The obtained polymer solution was used as a coating solution in order to coat, by dipping, a thin film over a porous support (NADIR UF membranes with MWCO=50 kDA), whereas the coating was done only on the upper selective side of the support membrane (without coating material being applied to the under, more porous, side). After preparation, the membranes were cured at 85 C. for 1 hour. After solvent evaporation and drying for several hours, the membrane could be used.

[0232] The characteristics of each of the new membranes are provided in Table 1 below. All permeabilities (OMTC) were calculated from Total Phenol data obtained in dialysis cell. All membranes in Table 1 used a 50 kDa UF support.

[0233] All the membranes that were made had a thickness of about 1-5 microns, based on polymer concentrations in the solutions and by setting a gap between the spreading blade and the membrane support to control the thickness of polymer solution coating the membrane support. The coating could be made thicker up to 10 microns.

TABLE-US-00002 TABLE 1 dibutyltin Overall Sample # and Polymer, ml, dilaurate TEOS Cross- mass membrane as 10% Catalyst ml, linker, ml, Mass transfer composition solution in 1% solution 5% solution flux coefficient, (polymer type) THF in THF in THF mg/m.sup.2 * sec m/sec #75. 0.3 ml 0.5 ml 0.1 ml 2.85 4.3 * 10.sup.6 PTFS 100% #76 PTFS = 0.56 ml, 0.4 ml 0.07 ml PTFS: PV4P PV4P = 0.14 ml, (8:2) #77 PTFS = 0.42 ml, 0.5 ml 0.08 ml 50 kDa PV4P = 0.28 ml PTFS:PV4P (6:4) #78 PTFS = 0.56 ml,, 0.4 ml 0.07 ml PTFS:PV4P (8:2) + PV4P = 0.14 ml, Tyrosol Tyrosol = 0.5 m, #79 PTFS = 0.42 ml, 0.5 ml 0.08 ml PTFS:PV4P (6:4) + PV4P = 0.28 ml Tyrosol Tyrosol = 0.5 ml #93 0.27:0.03 ml 0.4 ml 0.1 ml 3.24 4.8 * 10.sup.6 PTFS:PV4P = 9:1 #94 0.24:0.06 ml 0.5 ml 0.2 ml 3.67 3.85 * 10.sup.6 PTFS:PV4P = 8:2 #95 0.27:0.03 ml 0.5 ml 0.8 ml 2.43 4.40 * 10.sup.6 PTFS:PV4P = 9:1 #97 0.18:0.12 ml 0.8 ml 0.6 ml 2.84 5.06 * 10.sup.6 PTFS:PV4P = 6:4 #98 0.15:0.15 ml 0.8 ml 0.8 ml 3.79 5.15 * 10.sup.6 PTFS:PV4P = 1:1 #99 0.15:0.15 ml 0.8 ml 0.8 ml 3.1 4.62 * 10.sup.6 PTFS:PV4P = 1:1 without curing at 85 C. #100 0.3 ml 0.5 ml 0.1 ml 4.25 * 10.sup.2 2.19 * 10.sup.8 PTFS 100% on PP Pure PP 1.2 * 10.sup.1 1.7 * 10.sup.7 nonwoven support UF 50 kDa 11.6 10.74 * 10.sup.6

[0234] Table 2 shows the results of the a flow cell membrane contactor unit fitted with membrane #75, for extracting components of OMWW from NF or RO concentrates.

TABLE-US-00003 TABLE 2 Flux of polyphenols for different feeds treated in membrane contactor with membrane #75. Overall Mass mass Feed Permeate transfer transfer components, components, flux, coefficient, Feed source ppm ppm mg/m.sup.2 * sec m/sec Concentrate after NF Tyrosol 14.7 Tyrosol 3.84 5.08 * 10.sup.2 3.46 * 10.sup.6 with use NF-270 at 20 bar Concentrate after NF Hydroxytyrosol Hydroxytyrosol 1.59 * 10.sup.2 4.96 * 10.sup.6 with use NF-270 at 3.2 1.2 20 bar Concentrate after NF Gallic Acid Gallic Acid 2.78 * 10.sup.2 1.34 * 10.sup.6 with use NF-270 at 20.8 2.1 20 bar Concentrate after Tyrosol 565 Tyrosol 9.6 1.27 * 10.sup.1 2.25 * 10.sup.7 reverse osmosis RO-1 Concentrate after Hydroxytyrosol Hydroxytyrosol 3.84 * 10.sup.1 4.5 * 10.sup.7 reverse osmosis RO-1 853 29 Concentrate after Gallic Acid 82 Gallic Acid 2.25 * 10.sup.2 2.74 * 10.sup.7 reverse osmosis RO-1 1.7 Concentrate after Tyrosol 840 Tyrosol 3.8 5.03 * 10.sup.2 5.98 * 10.sup.8 reverse osmosis RO-2 Concentrate after Hydroxytyrosol Hydroxytyrosol 1.07 * 10.sup.1 7.74 * 10.sup.8 reverse osmosis RO-2 1385 8.1 Concentrate after Gallic Acid 69 Gallic Acid 8.6 * 10.sup.3 1.25 * 10.sup.7 reverse osmosis RO-2 0.65

[0235] Table 3 shows the overall mass transfer coefficients for Membrane #76 (PTFS:PV4P=8:2) for different polyphenol components in a feed of NF concentrate. From this the selectivity can be calculated and shows that the membrane was most permeable to hydroxytyroxol followed by tyrosol followed by gallic acid.

TABLE-US-00004 TABLE 3 Overall mass Feed Permeate transfer components, components, Mass transfer coefficient, Feed source ppm ppm flux, mg/m.sup.2 * sec m/sec Concentrate after Tyrosol 14.3 Tyrosol 4.4 5.82 * 10.sup.2 4.07 * 10.sup.6 NF with use NF-270 at 20 bar Concentrate after Hydroxytyrosol Hydroxytyrosol 2.38 * 10.sup.2 4.58 * 10.sup.6 NF with use NF-270 5.2 1.8 at 20 bar Concentrate after Gallic Acid Gallic Acid 7.14 * 10.sup.2 3.88 * 10.sup.6 NF with use NF-270 18.4 5.4 at 20 bar

[0236] Table 4 shows the selectivity results for Membrane #77 (PDMS:PV4P=6:4)

TABLE-US-00005 TABLE 4 Mass Overall mass Feed Permeate transfer transfer components, components, flux, coefficient, Feed source ppm ppm mg/m.sup.2 * sec m/sec Concentrate Tyrosol 13.6 Tyrosol 4.7 6.22 * 10.sup.2 4.57 * 10.sup.6 after NF with use NF-270 at 20 bar Concentrate Hydroxy- Hydroxy- 2.25 * 10.sup.2 5.92 * 10.sup.6 after NF with tyrosol 3.8 tyrosol 1.7 use NF-270 at 20 bar Concentrate Gallic Acid Gallic Acid 3.31 * 10.sup.2 1.48 * 10.sup.6 after NF with 22.4 2.5 use NF-270 at 20 bar

[0237] Table 5 shows the effect of selective membrane crosslinker concentration on composite Membranes (for a 50K UF support) in terms of phenol flux and Salt rejection (1000 ppm NaCl).

TABLE-US-00006 TABLE 5 Cross-linker Selective layer TEOS, 0.1% Mass polymer in n- flux, mg/m2, OMTC, Na composition hexane, ml sec, 10.sup.3 m/sec, 10.sup.4 rejection, % #42 PDMS-2 0.2 9.6 1.05 61.4 #43 PDMS-2 0.4 8.6 0.94 66.1 #44 PDMS-1 + 0.3 9.8 1.08 57.5 PTFS = 1:10 #45 PDMS-2 0.6 6.1 0.65 80.3 #47 PDMS-1 + 0.4 6.4 0.68 74.4 PTFS = 2:8 #48 PDMS-2 0.8 5.8 0.62 93.8 #50 PDMS-1 + 0.7 7.6 0.82 91.8 PTFS = 4:6 Dana's data Not available 2.38 0.26 Not available Livingston data Not available Not 0.31 Not available available

[0238] In another experiment, after 30 hours of operation the tyrosol/coumaric selectivity factor (Cp/Cf)tyrosol/(Cp/Cf)coumaric increased from 1.15 for a pure PTFS membrane (#75) to 2.42 for a PTFS:PV4P membrane (#97, PTFS:PV4P/6:4).

Example 2: Preparation of Composite Membranes Using Different Support Membranes

[0239] Membrane 94 (PTFS:PV4P 8:2) was prepared as described in Example 1 using different supports upon which the selective layer was coated: These supports included UF membranes of 50 kDa, 100 kDa, 150 kDa, and 300 kDa MWCO whose polymer matrices are based on stable engineering plastics such as polyethersulfone and polysulfone.

[0240] FIG. 2 discloses the effect of UF support on PTFS composite membrane permeability of phenol. The selective PTFS layer thickness was estimated as 1-3 m. FIG. 2 shows that the composite membranes on the more open UF supports (namely, having a higher MW cutoff) had higher mass flux and OMTC than the tighter UF membranes (having a lower MW cutoff).

Example 3: Preparation of Multilayered Membranes

[0241] In this example membranes using similar chemistry to what is described in the previous examples were used to make multilayered membranes.

[0242] The composition of several multi-layered membranes is presented in Table 6 below.

[0243] Membrane 80 is an example of a double layered selective membrane on a UF support, wherein the first layer on the UF support is PV4P with tyrosol, followed by a layer comprising PTFS:PV4P (6:4).

[0244] Membrane 81 is an example of a triple layer wherein the first layer on the UF support is PTFS:PV4P (6:4). The middle layer membrane is of PV4-P with tyrosol, followed by a top layer of PTFS:PV4P (6:4).

TABLE-US-00007 TABLE 6 Dibutyltin Tetraethyl Membrane dilaurate, orthosilicate, Polymer # and catalyst, crosslinker, Coating solution support Polymer ml ml solvent concentration, % #80 1.sup.stlayer: 0.2 0.035 THF 5 New double PV4P = 0.7 ml, layer Tyrosol = 0.2 ml membrane 2.sup.nd layer: 0.2 0.035 THF 5 50 kDa PTFS 0.42 ml, PV4P = 0.28 ml (6:4) #81 1.sup.st layer: 0.2 0.035 THF 5 New multi- PTFS = 0.42 ml, layer PV4P = 0.28 ml membrane (6:4), 50 kDa 2.sup.nd layer: 0.2 0.035 THF 5 PV4P = 0.7 ml, Tyrosol = 0.2 ml 3.sup.rd top layer: 0.2 0.035 THF 5 PTFS 0.42 ml, PV4P = 0.28 ml (6:4)

[0245] The Results of operating two membrane contactors fitted with different membranes on a common feed, which was an NF concentrate, are presented in Table 7, showing the selectivity of a bi-layered membrane (#80), in comparison to a single-layered membrane (#77). In this experiment the contactor was operated at 50 C. and the analysis of the recycling permeate (strip) solution composition was done after 24 hours of continuous operation of the membrane contactor.

TABLE-US-00008 TABLE 7 Hydroxytyrosol Ratio (%) Stream and Tyrosol TOC hydroxytyrosol + Tyrosol descriptor g/L g/L of TOC Feed (start -> 13.3 --> 6.6 65 --> 40 12.8 -->10.4 finish) Permeate from 0.425 1.21 21.9 Membrane 77 Single layer Permeate from 0.537 1.32 25.3 Membrane 80 bi-layer

Example 4: Biodegradation of Olive Oil Mill Permeate in Batch Mode Operation

[0246] This example describes the biodegradability of the NF permeate obtained after removing the polyphenols concentrate, namely the permeate number 9 of the scheme presented in FIG. 5. [0247] 1. Preparation of olive oil mill permeate in two different dilutions (1:5 and 1:10) with and kept in two 1 L Erlenmeyer flask. These dilutions represent dilution of NF OMW permeate with standard domestic wastewater stream fed to a wastewater treatment plant. The MBR sludge was added to each of the flask and the initial VSS concentration was measured to be 0.5 g/L in both the flasks. [0248] 2. The pH was maintained near neutral by adding calcium hydroxide solution. [0249] 3. The flasks were kept in a shaker water bath and the temperature was maintained at 27 C. [0250] 4. The air was pumped into the flasks through stone diffusers [0251] 5. The samples from both the flasks were taken at different time intervals and the reduction in the DOC concentration with time was measured.

[0252] Results:

TABLE-US-00009 Time (hours) DOC (mg/l) 1:5 DOC (mg/l) 1:10 0 648 404.8 24 131.4 41.6 48 74.8 34 68 52.7 20.8 97 49.5 18.8 120 33.2 18 144 20 16.4