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Membrane Filtration of Agro‐ industrial Wastewaters and Isolation of Organic Compounds with High Added Value

D.P. Zagklis, and C.A. Paraskeva, Department of Chemical Engineering, University of Patras

Presentation Outline

• Purification of olive mill wastewater phenols
• Purification of grape marc phenols
• Purification of olive leaf phenols
• Preliminary design of phenols purification plant

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Scope

• Large amounts of agricultural byproducts are produced every year, some of

them rich in phenolic compounds.

• Phenols are antioxidants with high‐added value and positive effects to the

human health.

• Their separation for the production of cosmetic products, food supplements

etc., is of great interest.

• For this purpose, a combination of solid‐liquid extraction, membrane filtration

and resin adsorption/desorption following by evaporation is proposed, for the production of phenolic concentrates.

• The final products of the proposed process contain a large percentage of the

byproducts’ phenolic content, in a small fraction of the initial volume.

• This technique, after modification, can be applied to a variety of phenol‐rich

byproducts, allowing the operation of phenol separation plant adjustable to local agricultural activities.

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Physicochemical Separation Techniques

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• Solid‐liquid extraction is the separation of target compounds

from a solid matrix through the use of the appropriate solvent.

• Membrane filtration is a separation technique that has many

applications in chemical process industries.

• Adsorption is the selective separation of a solute (adsorbate) from

a mixture, which is concentrated on the surface of a solid (adsorbent).

• Vacuum Evaporation for the final condensation of the isolated

compounds

Olive Mill Wastewater Phenolic Compounds

• Olive mill wastewater (OMW) is a

byproduct of the three‐phase extraction systems during the production of olive

• il.
• Because of their partition coefficient,

most phenolic compounds of olive fruits end up in the wastewater produced and not in olive oil.

• Oleuropein

is the most common phenolic compound of unripe olive fruits, but during maturity it is hydrolyzed to several simpler phenolic compounds like hydroxytyrosol and tyrosol.

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5 Oleuropein Hydroxytyrosol Tyrosol

Membrane Filtration of OMW

[g/L]

Initial OMW Sieving <0.125 mm UF Conc. UF Filtr. NF Conc. NF Filtr. RO Conc. RO Filtr. COD 107.23 99.08 257.73 51.10 61.03 32.72 65.48 6.47 TS 63.4 58.8 121.36 37.35 43.82 22.15 60.44 1.48 TSS 44 33 141 1.33 1.77 0.95 1.67 0.08 Ch 12.34 13.19 19.37 10.93 11.97 5.09 14.96 0.21 Ph 2.64 2.65 6.59 2.17 2.64 0.86 2.09 0.04

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Resin Adsorption/Desorption of OMW ROc

• XAD4 and XAD16N yielded the best results. Even though the sample contained more carbohydrates than

phenols, resins adsorbed the dissolved phenols at a higher percentage.

• When water was used as a desorption solvent, the small amount of carbohydrates that was adsorbed on the

resin was desorbed at a high percentage (60%). Ethanol, on the other hand, almost selectively removed the adsorbed phenols, while acetone removed both, carbohydrates and phenols.

• Kinetic experiments allowed the optimization of flow rates and total volume of treated sample before the

resin surface was saturated.

29/6/2016 ΔΙΑΧΩΡΙΣΜΟΣ, ΑΠΟΜΟΝΩΣΗ ΚΑΙ ΕΜΠΛΟΥΤΙΣΜΟΣ ΦΑΙΝΟΛΙΚΩΝ ΕΝΩΣΕΩΝ ΑΠΟ ΑΓΡΟΤΙΚΑ ΠΑΡΑΠΡΟΙΟΝΤΑ ΜΕ ΦΥΣΙΚΟΧΗΜΙΚΕΣ ΜΕΘΟΔΟΥΣ 7

20 40 60 80 100 120 20 40 60 80 100

XAD4 XAD7HP XAD16N

% Phenols Adsorbed g of Resin/L of Sample (a)

20 40 60 80 100 120 20 40 60 80 100

XAD4 XAD7HP XAD16N

% Carbohydrates Adsorbed g of Resin/L of Sample (b)

Triple Distilled Water Ethanol Acetone

20 40 60 80 100

Carbohydrates Phenols

% Desorption

Solvent

2 4 6 8 10 12 20 40 60 80 100 12 rv/h Ph 6 rv/h Ph 3 rv/h Ph 12 rv/h Ch 6 rv/h Ch 3 rv/h Ch

% Adsorption Filtrated Volume (rv) (a)

2 4 6 8 10 12 20 40 60 80 100

Carbohydrates Phenols

% Desorption with water Filtrated Volume (rv) (b)

1 2 3 4 5 6 20 40 60 80 100

Carbohydrates Phenols

% Desorption with ethanol Filtrated Volume (rv) (c)

Final Concentrate of OMW Phenolic Compounds

Initial OMW RO concentrate Ethanolic resin effluent Distillation residue Volume, mL 16700 2000 1500 9 Phenols, g/L 2.64 ±0.04 2.09 ±0.02 2.36 ±0.01 377.50 ±8.34 Carbohydrates, g/L 12.34 ±0.49 14.96 ±0.03 3.84 ±0.01 293.92 ±1.28

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• After

carbohydrates removal via the proposed resin process, the distillation under vacuum (‐0.95 bar, 55 °C) of the resin ethanolic effluent resulted to a final phenol concentration of 378 g/L in gallic acid equivalents in the distillation residue.

HPLC Analysis of Simple Phenols

Phenolic compound (mg/L) UF feed UF Filtr. UF Conc. NF Filtr. NF Conc. RO Conc. Desorbed From Resin Evap. Gallic acid 29.5 32.1 36.4 19.5 48.5 42.9 75.9 5908 Hydroxytyrosol 75.4 259.5 98.4 246.4 377.2 558.9 974 84775 Tyrosol 38.16 60.8 23.6 64.8 65.1 136 152.2 21072

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• The only phenolic compounds detected out of the ones tested were gallic acid,

hydroxytyrosol (HT) and tyrosol with HT being the dominant phenol.

• No phenols were in detectable levels in the RO filtrate. The membrane process purified the

low‐molecular‐weight phenols through sieving of all the compounds according to their molecular weight.

• The resin process further purified the phenols from the rest of the low‐molecular‐weight

compounds according to their polarity.

• After vacuum distillation, the phenolic compounds appear to withstand the heat process

and the final concentration of HT obtained in the distillation concentrate is around 85 g/L.

Grape Marc Phenolic Compound

• Grape cultivation is one of the

most important agricultural activities in the world with most of the produced grapes used in winemaking.

• In

the winemaking process a significant amount

• f

solid byproducts is produced originating from the skin and seeds of grapes after the juice extraction.

• Although part of the phenolic

content

• f

the grapes is transferred to the juice and later wine, the solid byproducts are rich in phenols, allowing the production

• f phenol‐rich extracts

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10 Catechin Epicatechin trans‐Resveratrol Quercetin

Extraction of Grape Marc Phenolic Compounds

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20 40 60 80 100 500 1000 1500 2000 2500 3000 3500

Phenols Carbohydrates

Extracted compound (mg/L) Ethanol % (v/v) (a)

1 2 3 4 5 500 1000 1500 2000 2500 3000 3500

Extracted compound (mg/L) HCl 1N (%) (b)

Phenols Carbohydrates

10 20 30 40 50 60 70 80 90 100 500 1000 1500 2000 2500 3000 3500

Extracted compound (mg/L) Time (min) (c)

Phenols Carbohydrates

50 100 150 200 250 300 500 1000 1500 2000 2500 3000 3500

Phenols Carbohydrates

Extracted compound (mg/L) Solid (g/L) (d)

Optimum extraction conditions Ethanol % 50 HCl 1N % 1 Duration 15 min Solids/Solvent 200 g/L Double extraction

Membrane Filtration of Grape Marc Extract

Sample Volume L mg/L Total carbohydrates Total phenols Catechin Quercetin Epicatechin Rutin Initial 80 2204 440 7.4 <1 1.8 1.4 UFf 60 1106 285 9.1 <1 2.1 1.8 NFc 15 1882 743 15.6 <1 2.3 3.0 NFf 45 443 23 3.8 <1 1.7 N/D

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Initial UFc UFf NFc NFf

• 20 kg of grape marc were extracted, with 50

L of extract occurring.

• Prior to membrane filtration, the extract was

sieved through stainless steel sieves with final pore diameter 0.125 mm. and ethanol was partly removed through distillation leading to 15 L of residue with 14% v/v ethanol (compared to 50% v/v). The extract was then diluted with water to 80 L.

Final Concentration of Grape Marc Phenolic Compounds

Sample Volume mL* mg/L Total carbohydrates Total phenols Catechin Quercetin Epicatechin Rutin Desorbed 4000 1951 3023 65.0 <1 13.0 31.0 Evap. 31 112333 190850 4746 60 853 381

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Final Concentrate

* The resin process was not applied in all of the NFc, the volumes presented occurred after scaling of the results.

• With the removal of carbohydrates from the

NFc, further concentration can be achieved through evaporation. For this purpose 2.4 L

• f NFc were treated with the proposed resin

process, leading to the production of 0.64 L

• f ethanolic effluent that was evaporated

under vacuum (0.05 bar, 50 °C). The final concentrate had a volume of 5 mL.

Olive Leaf Phenolic Compounds

• Olive leaves are a byproduct of
• live fruit harvesting and initial

stages

• f
• live
• il

extraction, during their separation from olive fruits.

• Olive

leaf extracts have been proven to be rich in phenolic compounds, with the most prominent one being oleuropein, which, unlike in the olive fruit, it is not hydrolyzed to simpler phenols.

• Oleuropein can be either bound to

a sugar molecule (Oleuropein glycoside) or be present in its free form (Oleuropein aglycon).

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14 Oleuropein

Extraction of Olive Leaf Phenols

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25 50 75 100 500 1000 1500 2000 2500 3000

Extracted compound (mg/L) Ethanol (% v/v) (a)

Phenols Carbohydrates

50 100 150 200 250 1000 2000 3000 4000 5000

Extratced compound (mg/L) Solids (g/L) (b)

Phenols Carbohydrates

30 60 90 120 150 180 210 2000 4000 6000 8000 10000

Extracted compound (mg/L) Time (min) (c)

Phenols Carbohydrates

Optimum extraction conditions Ethanol % Duration 120 min Solids/Solvent 250 g/L

Membrane Filtration of Olive Leaf Extract

Initial UF conc. UF filtr. NF conc. NF filtr. Volume L 75 17 58 9 49 Total Ph mg/L 468 ±15 774 ±3 325 ±7 988 ±25 88 ±1 Total Ch mg/L 2801 ±30 3458 ±27 2140 ±179 5410 ±37 1249 ±24

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Resin Adsorption/Desorption of Olive Leaf Extract NFc

• All three resins appeared to adsorb the phenols contained in the NF concentrate to an

acceptable extend, but, on the other hand, significant adsorption of carbohydrates took place as well.

• The high adsorption percentage of carbohydrates, indicate the presence of complex

compounds, like phenol glycosides, which can be detected as phenols and carbohydrates.

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20 40 60 80 100 120 140 160 180 200 20 40 60 80 100

XAD4 XAD7HP XAD16N

% Carbohydrate adsorption Resin (g/L)

20 40 60 80 100 120 140 160 180 200 20 40 60 80 100

XAD4 XAD7HP XAD16N

% Phenols adsorption Resin (g/L)

2 3 4 5 6 7 8 9 10 20 40 60 80 100

Ph 5 rv/h Ph 10 rv/h Ph 20 rv/h Ph 50 rv/h Ch 5 rv/h Ch 10 rv/h Ch 20 rv/h Ch 50 rv/h

% Adsorbed Filtrated Volume (resin volume)

1 2 3 4 5 6 10 20 30 40 50 60 70 80 90 100

Carbohydrates Phenols

% Desorbed with water Filtrated volume (rv)

1 2 3 4 5 6 10 20 30 40 50 60 70 80 90 100

Carbohydrates Phenols

% Desorbed with ethanol Filtrated volume (rv)

Final Concentration of Olive Leaf Phenols

Volume mL Total Phenols mg/L Total Carbohydrates mg/L NFc 1440 988 ±25 5410 ±37 Desorbed 720 1480 ±1 5260 ±35 Final concentrate 10 97890 ±1230 322333 ±3933

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• 1.44 L of NF concentrate were treated with

the proposed resin process, leading to the production of 0.72 L of ethanolic effluent that was evaporated under vacuum (0.05 bar, 50 °C). The final concentrate had a volume of 10 mL .

Oleuropein‐glycoside

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β‐glycosidase

+

+

esterase Glucose Hydroxytyrosol Oleuropein Elenoic acid Hydroxytyrosol Elenoic acid

Olive Leaf Extract‐Conclusions

• With the proposed method, significant separation of olive leaf phenols was achieved.

Firstly optimization of the extraction conditions was carried out, in terms of solvent ethanol percentage, solid/solvent ratio and duration.

• 20 kg of olive leaves were extracted with 80 L of water, and the extract was treated

with membrane filtration. In the UF step, the suspended particles were removed, while NF concentrated the majority of the contained phenolic compounds.

• With batch adsorption experiments, XAD16N was proven to have the best adsorption

behavior, and was used in resin packed beds to treat a larger amount of NF

• concentrate. The occurring resin ethanolic product contained 65% of the NF

concentrate phenols and 23% of the contained carbohydrates.

• The ethanolic product of the resin process was finally treated with vacuum

evaporation, with the finally product containing around 98 g/L phenolic compounds in gallic acid equivalents, compared to 0.5 g/L of the initial extract.

• This separation, although significant, was affected by the presence of complex

phenolic compounds, like oleuropein‐glycoside, part phenols and part carbohydrates.

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Phenols Purification Plant

• The combination of solid‐liquid extraction, membrane filtration and

resin adsorption/desorption could be modified and applied to a variety

• f byproducts rich in phenolic compounds.
• The seasonal nature of these byproducts makes the combination of

different byproducts imperative for the continuous operation of the plant.

• The viability of this endeavor strongly depends on the market demand
• f the high‐added value phenolic products and the management of the

high volumes of byproducts occurring from the proposed process.

• A preliminary design of such a plant was carried out, based on the

results obtained from the treatment of olive mill wastewater.

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Preliminary Design of Phenols Purification Plant

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300 m3 100 m3 100 m3 100 m3 100 m3 50 m3 100 m3

Initial waste storage tank (1) Solids tank (2) Pretreated waste tank (7) Oil tank (3) Decanter feed tank (4) vertical separator feed tank (5) filter press feed tank (6)

100 m3

UF feed tank (8)

200 m3

UF concentrate tank (18)

Pretreatment

Plant byproduct treatment capacity: 110 tn/h (2000 tn/d)

Preliminary Design of Phenols Purification Plant

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100 m3

UF filtrate tank (9)

100 m3

NF filtrate tank (11)

200 m3

RO filtrate tank (13)

UF NF RO

50 m3

RO concentrate tank (14)

100 m3 100 m3 100 m3

50 m3

Not adsorbed and water desorbed tank (15)

Water Ethanol 95%

Ethanolic effluent tank (16)

1 m3 Final

concentrate tank (17)

100 m3

NF feed tank (10)

100 m3

RO feed tank (12)

250 m3

NF concentrate tank (19)

Preliminary Design of Phenols Purification Plant

Source Main product Harvesting period Tomato byproducts Quercetin, Hydroxycinnamic acids and lycopene May-August Coffee byproducts Hydroxycinnamic acids All year Citrus byproducts Hesperidin November-March Apple, pear byproducts Hydroxycinnamic acids September-January Strawberry byproducts Anthocyanins May-July Mediterranean aromatic plants (dyctamus, marjoram, vitex, teucrium, rosemary) Phenolic acids June-August

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General Conclusions

• Solid‐liquid extraction, membrane filtration and resin adsorption/desorption

were combined for the purification of phenols contained in olive mill wastewater, grape marc and olive leaves.

• For the solid materials examined, correct extraction was crucial for

maximizing the phenolic concentration. Moreover, pretreatment of the samples can greatly affect the results, as for example reduction of olive leaf particle size may increase the amount of phenols extracted, with lower extraction durations, or defatting of cocoa powder can prevent the hindrance that was exhibited due to high fat percentage.

• During membrane filtration, the extracted compounds were fractionated

according to their molecular weight. In the UF step, the solids contained in the samples were removed. The complex and higher molecular weight compounds were concentrated in the NF step, while low molecular weight at the RO step.

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General Conclusions

• After the selective adsorption of the phenolic compounds of the membrane

concentrate of interest, water was used to desorb the adsorbed carbohydrates and ethanol for the desorption of phenols.

• During the resin process, the solvent of the phenolic compounds was changed

from water to ethanol, facilitating their further concentration through

• evaporation. The final product of the proposed process contains a large

amount of the phenols contained in the initial plant material, in a very small fraction of the initial volume

• Apart from the plant materials examined in this study, the proposed process

can be employed for the treatment of any material rich in phenolic

• compounds. A preliminary design of a treatment plant was presented, that

can be adjusted for the extraction of phenols from regional agro‐industrial byproducts, with some phenol‐rich byproduct proposals as well.

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I would like to thank:

• Prof. P. Koutsoukos

Dimitris Zagklis, Ph.D

• I. Iakovides, Ph.D student
• A. Pantziaros, Graduate Student
• E. Pavlakou, Graduate Student

Spyros Kontos, Ph.D student

Laboratory ofTransport Phenomena and Physicochemical Hydrodynamics

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References

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Dimitris P. Zagklis, PhD Dissertation, ‘Separation, isolation and enrichment of phenolic compounds from agricultural byproducts with physicochemical methods’, November 2, 2015, Patras

• D. P. Zagklis & C. A. Paraskeva, “Purification of grape marc phenolic compounds

through solvent extraction, membrane filtration and resin adsorption/desorption”, Separation and Purification Technology, 156 (2015), 328-335

• D. P. Zagklis, A. I. Vavouraki, M. E. Kornaros & C. A. Paraskeva, “Purification of olive

mill wastewater phenols through membrane filtration and resin adsorption/desorption”,

• J. Hazard. Mater. 285 (2015) 69-76.
• D. P. Zagklis & C. A. Paraskeva, "Membrane filtration of agro-industrial wastewaters

and isolation of organic compounds with high added values", Water Sci. Technol. 2014, 69(1), 202-207.