sign in sign up
<<
Home , Membrane distillation, Nanofiltration

Outline: Micro-, ultra- and –

1. Where to use what RO and

2. How they work – Functions and applications 3. Examples: Concentrating Proteins Concentrating By Secondary Metabolites Concentrating Birch Sap Knud Villy Christensen, Lene Fjerbæk Søtoft, Birgir Norddahl, Morten Ohm, Henrik Karring, Juncal Martin, Martin Valgreen, Lars Toft Madsen, Kasper Hansen

Department of Chemical Engineering, Biotechnology and Environmental Technology University of Southern Denmark Micro-, ultra- and nanofiltration –RO and

Outline: Some of the present day work horses in :

1. Where to use what and Food industry: (MF) 2. How they work (UF)

3. Examples: Water purification: Concentrating Proteins Nanofiltration (NF) Concentrating Secondary Metabolites (RO) Concentrating Birch Sap Some old prospects that has yet to find favor: Membrane distillation – MD Direct Contact Membrane Distillation (DCMD) Osmotic Membrane Distillation (OMD) Sweep Gas Membrane Distillation (SGMD) Vacuum Membrane Distillation (VMD) Micro-, ultra- and nanofiltration –RO and membrane distillation Where to use what based on size exclusion:

Particle size [μm] 0.001 0.01 0.1 1 10 [nm] 1 10 100 1000 10000 Molecular weight 100 200 1000 105 5·105

Salts Colloids Yeast cells Viruses Bacteria Solutes Metal ions Proteins and peptides Sugars Microsolutes

Nanofiltration Membrane Ultrafiltration process RO Microfiltration Membrane Distillation Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Microfiltration:

1. Where to use what Well defined pore structure: Can be homogeneous:

2. How they work

3. Examples: Concentrating Proteins Concentrating Secondary Metabolites Concentrating Birch Sap or heterogeneous: Microfiltration layer

Support layer Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Microfiltration:

1. Where to use what The process is done in cross flow and is forced through by a difference in 2. How they work

Feed Side I: PI 3. Examples: liquid Concentrating Proteins Concentrating Secondary Metabolites Membrane Concentrating Birch Sap

Side II: PII

PI > PII

Separation is based on pore size and particle size Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Microfiltration:

1. Where to use what Characterisation of microfiltration :

2. How they work Mean pore size: Dp [m] Porosity: ε 3. Examples: Tortuosity:  Concentrating Proteins Concentrating Secondary Metabolites Concentrating Birch Sap Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Microfiltration:

1. Where to use what As pore sizes are not sharply defined: 2. How they work Pore size distribution:

3. Examples: Older type of Newer type of Concentrating Proteins MF membrane MF membrane Concentrating Secondary Metabolites Concentrating Birch Sap

The size of retained particles are also a distribution, not a clear size cut Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Ultrafiltration:

1. Where to use what Well defined pore structure: Allways heterogeneous:

2. How they work

3. Examples: Concentrating Proteins Concentrating Secondary Metabolites Concentrating Birch Sap Ultrafiltration layer

Support layer Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Ultrafiltration:

1. Where to use what The process is done in cross flow and liquid is forced through by a difference in pressure 2. How they work Feed Side I: PI 3. Examples: liquid Concentrating Proteins Concentrating Secondary Metabolites Membrane Concentrating Birch Sap

Side II: PII

PI > PII

Separation is based on pore size, macromolecular size and shape Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Ultrafiltration:

1. Where to use what Characterization of ultrafiltration membranes:

2. How they work Mean pore diameter: Dp [m] Porosity: ε 3. Examples: Tortuosity:  Concentrating Proteins Concentrating Molecular Weight Cut Off: MWCO [Da] Secondary Metabolites Concentrating Birch Sap Definition of MWCO

100 90 95% 80 70 60 50 40 30 20 Retention [%] 10 MWCO 0 Molecular weight [Dalton] Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: RO and nanofiltration:

1. Where to use what Pores are often not well defined: Allways heterogeneous:

2. How they work

3. Examples: Concentrating Proteins Concentrating Secondary Metabolites Concentrating Birch Sap Transport is by through a polymer chain layer Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: RO and nanofiltration:

1. Where to use what The process is done in cross flow and liquid is forced through by a difference in pressure 2. How they work Feed Side I: P 2+ 3. Examples: I + liquid 2+ 2+ 2+ Concentrating Proteins Concentrating Secondary Metabolites + Membrane Concentrating Birch Sap + + 2+ + Side II: PII

PI > PII

Separation is based on molecular size, solubility and charge Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: RO and nanofiltration

1. Where to use what Characterization of RO and nanofiltration membranes:

2. How they work

3. Examples: Concentrating Proteins Concentrating Secondary Metabolites Concentrating Birch Sap

Salt rejection:

∙ ∙ ∙ Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Microfiltration, Ultrafiltration, RO and Nanofiltration

1. Where to use what Feed: Retentate: What is retained by 2. How they work What is lead to the membrane the membrane 3. Examples: Concentrating Proteins Concentrating Secondary Metabolites Concentrating Birch Sap

Permeate: What pass through the membrane Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Microfiltration, Ultrafiltration, RO and Nanofiltration

1. Where to use what Process related terms:

2. How they work

3. Examples: Concentrating Proteins Concentrating Secondary Metabolites Concentrating Birch Sap

Selectivity: CAp CAp   CAf CAr  AB = or:  AB = CBp CBp   CBf CBr Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Microfiltration, Ultrafiltration, RO and Nanofiltration

1. Where to use what Process related terms:

2. How they work

3. Examples: Concentrating Proteins Concentrating Secondary Metabolites Concentrating Birch Sap

Flux: Industrial unit:

∙ ∙ Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Microfiltration, Ultrafiltration, RO and Nanofiltration polarization. gel formation and fouling: 1. Where to use what

2. How they work

3. Examples: Concentrating Proteins Concentrating Secondary Metabolites Concentrating Birch Sap

Here the flux can be described by the formula:

v = Qm ( P membran ) Where -1 -1 Qm is the permeability [m·Pa ·s ] ∆Π is the differense in osmotic pressure across the membrane [Pa] Micro-, ultra- and nanofiltration –RO and membrane distillation How they work:

Outline: Microfiltration, Ultrafiltration, RO and Nanofiltration

1. Where to use what The osmotic pressure can be described by the virial equation: 2. How they work 2 nnnBBB 3. Examples: = R T 1 B + C  ...... VVV Concentrating Proteins  Concentrating Where:

Secondary Metabolites 3 Concentrating Birch Sap V is the liquid volume [m ]

nB is mole of dissolved matter in the liquid [mol] B, C etc. are experimental constants

For proteins, polysaccharides and other macro molecules, the van Hoff’t approximation can be used: n  = B R T V Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what Membrane contactors can best be defined as units where a porous membrane is used to 2. How they work a. Separate two, normally miscable, to enable selective 3. Examples: extraction of one or more components from one liquid to the Concentrating Proteins other. Concentrating Secondary Metabolites Concentrating Birch Sap b. To enhance vaporization area per volume of a liquid and shorten the distance between surface and surface

In both cases the membrane does not contribute to the selectivity of the process, as the membrane pores are much larger than the molecules to be separated by the process. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what The basic concept of membrane contactors can be illustrated as:

2. How they work Feed Side I liquid 3. Examples: Concentrating Proteins Concentrating Membrane Secondary Metabolites Concentrating Birch Sap Vapor Side II filled pores The driving force behind the process is a difference in the chemical potential between side I and II of the membrane. The transport mechanism through the pores depends partly on how this difference in chemical potential is achieved. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what The basic concept of membrane contactors can be illustrated as:

2. How they work Feed Side I liquid 3. Examples: Concentrating Proteins Concentrating Membrane Secondary Metabolites Concentrating Birch Sap Vapor Side II filled pores It is the combination of the difference in the chemical potential and tranport rate that determines the selectivity of the process, not the membrane. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what Wetting of a membrane contactor

2. How they work Feed Side I liquid 3. Examples: Concentrating Proteins Concentrating Membrane Secondary Metabolites Concentrating Birch Sap Liquid Side II filled pores For the process to work as a membrane contactor the pores have to stay vapor filled. If liquid penetrates the pores the membrane is said to be wetted and works as a normal microfiltration or ultrafiltration membrane. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what To avoid wetting of a membrane contactor

2. How they work Feed Side I liquid 3. Examples: Concentrating Proteins Concentrating Membrane Secondary Metabolites Concentrating Birch Sap Side II The forces necessary to force liquid into the pores can be described by the LaPlace equation: Membrane liquid ∙ℓ ∙ℓ contact angle ∆ Pressure difference Pore radius across membrane between liquid at initial wetting and membrane Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what To avoid wetting of a membrane contactor

2. How they work Feed Side I liquid 3. Examples: Concentrating Proteins Concentrating Membrane Secondary Metabolites Concentrating Birch Sap Side II The demand that ∆ under operation has to be below the pressure difference of initial wetting severely limits the choice of available membrane materials, process conditions and usefullnes of membrane contactors. Micro-, ultra- and nanofiltration –RO and membrane distillation Classification of membrane contactor processes

Membrane contactor processes

DCMD: AGMD Direct Contact Air Gap Membrane Membrane distillation. Distillation. Driving Force: Driving Force: Vapor removed by Temperature condensation on a driven change in cold surface vapour pressure

OMD: EMD SGMD VMD Osmotic Extractive Sweep Gas Vacuum Membrane Membrane Membrane Membrane Distillation. Distillation. Distillation Distillation. Driving Force: Driving Force: Driving force: Driving force: Vapor removed by Osmotic draw Change i vapor Continous vacuum suction driven pressure removal of vapor change in vapour due to chemical by an inert sweep pressure. modification of gas Can be combined diffusing molecule with DCMD. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what Direct Contact Membrane Distillation

2. How they work Feed Side I, Hot side TI liquid 3. Examples: y=0 Concentrating Proteins Concentrating Membrane Secondary Metabolites y=δ Concentrating Birch Sap Draw Side II, Cold side T II liquid

, ∙ ∙ ∙ ∙ Works like a normal . The short way the vapor has to travel between hot and cold reservoir gives in theory a smaller equipment size compared to , this is off-set though by the fact that all heat for the evaporation and all cooling for the condensation have to be brougth in by the feed and draw liquid respectively, which limits the size of each membrane module. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what Osmotic Membrane Distillation

2. How they work Feed Side I, Hot side TI liquid 3. Examples: y=0 Concentrating Proteins Concentrating Membrane Secondary Metabolites y=δ Concentrating Birch Sap Draw Side II, Cold side T II liquid

, ∙ ∙ ∙ ∙ Works like exept that evaporation of the liquid is needed and that the process can be boosted by running a temperature difference as well. It can be used for concentrating liquid of heat sensitive components just as DCMD, but has the same drawback as forward osmosis. The draw solution have to be reclaimed. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what Extractive Membrane Distillation

2. How they work Feed Side I, TI liquid 3. Examples: y=0 Concentrating Proteins Concentrating Membrane Secondary Metabolites y=δ Concentrating Birch Sap Draw Side II, T I liquid

, ∙ ∙ ∙ ∙ Works like forward osmosis exept that evaporation of the components selectively extracted is needed . The process would normally be run with feed liquid and draw solution at the same temperature to avoid evaporation of solvent (water) to the draw solution. As for forward osmosis and OMD the draw liquid need to be regenerated or be a commercially interesting product. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what Sweep Gas Membrane Distillation

2. How they work Feed Side I, TI liquid 3. Examples: y=0 Concentrating Proteins Concentrating Membrane Secondary Metabolites y=δ Concentrating Birch Sap Sweep Side II, T II gas

, ∙ ∙ In SGMD a sweep gas continously remove vapor or gas that has permeated through the membrane from the membrane surface . The process competes with evaporation or packed column gas strippers. As the membrane just works as an extra barrier against transport its main advantages compared to column strippers is the possibility of a higher liquid-to-gas interphase. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what Vacuum Membrane Distillation

2. How they work Feed Side I, TI liquid 3. Examples: y=0 Concentrating Proteins Concentrating Membrane Secondary Metabolites y=δ Concentrating Birch Sap Side II, TII

, ∙ ∙ ∙ ∙ In VMD the vapor or gas that has permeated through the membrane is pumped away by either a vacuum pump or a condensor system. The process compete with pervaporation and vacuum evaporation. The process in general has higher flux than pervaporation but lower selectivety as the membrane does not contribute to the selectivity. Micro-, ultra- and nanofiltration –RO and membrane distillation How they work: Outline: Membrane Distillation - Basic Concepts

1. Where to use what Air Gap Membrane Distillation

2. How they work Feed Side I, TI liquid 3. Examples: y=0 Concentrating Proteins Concentrating Membrane Secondary Metabolites y=δ Concentrating Birch Sap

Side II, cold surface at TII , ∙ ∙ ∙ ∙ Condensate out In AGMD the vapor that has permeated through the membrane is condensed on a cold surface close to the membrane. The process competes with short distant condensor and distillation systems. It has mainly been tried out as a simple system for producing purified water from saline water. ConcentrationSalted Herring of Whey Marinade: Protein:

Purpose: Background: To reclaim fats, proteins and amino acids from the herring marinade and reduce water consumption in the herring curring process.

Initial composition: Prior SDS-PAGE and MALDI-TOF showed proteins and peptides: Choice of MWCO/membranes was based on this.

Process Membrane type Material Pore size/MWCO /Rejection MF Alfa Laval- MFP2 Fluoropolymer 0.2 μm UF50 DSS-GR51PP Polysulphone 50 kDa

UF20 Alfa Laval-FS61PP Fluoro polymer 20 kDa

UF10 DSS-ETNA10PP Composite fluoro 10 kDa polymer UF09 Alfa Laval-ETNA01PP Fluoro polymer 1 kDa

NF Alfa Laval-NF Polyamide on Reject > 98% MgSO4 polyester (2000 ppm, 9 bar, 25ºC) SDS-PAGE: Dodecyl RO RO98pHt Composite on Reject > 97% NaCl Sulphate-PolyacrylAmide polypropylene (2000 ppm, 16 bar, 25ºC) Gel Electrophoresis ConcentrationSalted Herring of Whey Marinade: Protein: Suggested conceptual process design:Background: ConcentrationSalted Herring of Whey Marinade: Protein: Suggested conceptual process design:Background: ConcentrationSalted Herring of Whey Marinade: Protein: Suggested conceptual process design:Background: ConcentrationSalted Herring of Whey Marinade: Protein: Suggested conceptual process design:Background:

Constant ash content

RO not possible due to high salt content: Δπ ~70 bar Salted Herring Marinade: Experienced problems during experiments: Fouling is a server problem, if prefiltering is not carried out. Membrane flux declines fast

Results obtained: Instead of having 120 L waste water: 7 L fat value added products, fodder, ( biogas) 20 L Fish remains and particles (OM) fodder, (biogas ) 4 L retentate UF50 (good recovery of protein) proteins 3 L Retentate NF (sugars, amino acids & peptides)value added products, reuse of sugars 50 L Permeate NF (water & salt) reusable water with salt and little sugars and OM 36 L residual waste water with salt for treatment or reuse ConcentrationWillow extract of Whey concentrate: Protein: Purpose: Background: To produce a willow extract concentrate which with close to original composition except for water including inorganic salts

Chemical structures: Natural metabolites: Synthesized product:

Salicin Saligenine Salisylic acid Condensed tanines

Salisylic acid acetate Salicortin Flavonoids derived (Aspirin) from flavan ConcentrationWillow extract of Whey concentrate: Protein: Identified production problems: Background: Flavenoids and condensed tannins are heat sensitive Only water is to be removed There is a risk of microbial growth, but conservation additives should be avoided as the product is to be sold as natural medicament Drymatter content is to be increased from 0.1% to 5-16% Willow extract concentrate:

Suggested conceptual process design: Willow extract

Sive Large solids

MF Microbes

UF Vira

RO Water

Concentrate Willow extract concentrate:

Suggested conceptual process design: Willow extract

Total filtrate amount: 350 liters Sive Large Microfilter: AlfaLaval FSMO, 45PP solids Total filter area: 0.216 m2 ΔP: 2 bar MF Microbes

UF Vira

RO Water

Concentrate Willow extract concentrate:

Suggested conceptual process design: Willow extract

Sive Large solids

MF Total filtrate amount: 212 liters Microbes Ultrafilter: AlfaLaval GR81PP Total filter area: 0.288 m2 ΔP: 7.2 bar UF Vira

RO Water

Concentrate Willow extract concentrate:

Suggested conceptual process design: Willow extract

Sive Large solids

MF Microbes

UF Vira Total filtrate amount: 199 liters RO-membrane: AlfaLaval PO98pHt Total filter area: 0.288 m2 ΔP: 34.2 bar RO Water

Concentrate ConcentrationWillow extract of Whey concentrate: Protein: Experienced problems during experiments:Background: Fouling is experienced in each step, though severe irreversible fouling seems to be avoided Only a drymatter content of 5% can be reached with RO due to an unexpected high inorganic salt content

Results obtained: Concentration of willow extract using a combination of microfiltration, ultrafiltration and reverse osmosis works CIP with hot water, sodium hydroxide solution and citric acid solution is sufficient to restore the flux Further work is needed to increase the final drymatter concentration. A combination of nanofiltration reverse osmosis and DCMD should be tested ConcentrationBirch of WheySap: Protein: Purpose: To produce a colourless self preserving concentrate of 65 weight-% drymatter with close to original compositionBackground: except for water

Typical composition of Birch Sap:

Identified production problems: Amino acid and sugar leads to browning at elevated temperature due to Maillard reactions. Elevated temperatures lead to furfural formation from sugars in acidic media Birch sap is the perfect growth media for bacteria Birch Sap:

Suggested conceptual process design:

Birch Sap

Large Total filtrate amount: 178 liters Sive Microfilter: AlfaLaval DSS-FSMO,15PP solids Total filter area: 0.404 m2 ΔP: 2 bar MF Microbes

RO 16-17 Water ºBrix

DCMD Water

Concentrate Birch Sap:

Suggested conceptual process design:

Birch Sap

Total filtrate amount: 310 liters RO-filter: AlfaLaval DSS-HR98PP Large Total filter area: 0.404 m2 Sive ΔP: 35 bar solids

MF Microbes

RO 16-17 Water ºBrix

DCMD Water

Concentrate Birch Sap:

Experienced problems during experiments: Processing temperature has to be kept below 40°C to avoid furfural formation Microbial growth is a problem at low drymatter if MF is not implemented Slight colouring of product can not be avoided Low flux for DCMD

Results obtained: Total volume reduction: From 327 to 4.4 liters or by a factor of 73 The combination of microfiltration, reverse osmosis and DCMD can produce a birch sap concentrate of least 60 %-weight dry matter Membrane Technology Group

Whom to contact

Assoc. Prof. Birgir Norddahl: [email protected] Assoc. Prof. Knud Christensen: [email protected]

Ass. Prof. Lene Fjerbæk Søtoft: [email protected]

1 Lab. Technician and 4 PhD-students

What equipment do we have at our disposal: Microfiltration Ultrafiltration Nanofiltration Reverse Osmosis Membrane distillation Micro-, ultra- and nanofiltration –RO and membrane distillation

Acknowledgements: Biosynergy A/S for supplying birch sap Ny Vraa Bioenergi I/S for supplying willow extract Launis A/S for supplying salted herring

Part of Innovation Consortium Natural Ingredients and Green Energy - with sustainable purification technologies (NIGE)

Financially supported by Danish Agency for Science, Technology and Innovation

Questions?