Maria Norberta de Pinho

Instituto Superior Técnico/ICEMS

11th of March 2014

Membrane Processes for a Sustainable

Development

Objectives for the Development

of Sustainable Processes

More efficient and selective production with:

- reduction of raw materials, water, subsidiary

materials, and energy consumption

- treatment/recycling of process streams as process

water/solvent(s)/surplus raw materials

- treated wastewater reuse preventing degradation

of receiving water bodies and the environment

Potencial reuse/valorization of new products

The Role of Membrane Technology for the

Development of Sustainable Processes

Confinement of raw materials/polutents/secondary products inconcentrated fluxes envisaging their reuse/treatment/valorization

Integration of fractionation technologies with advanced treatmenttechnologies

Treatment of prioritary pollutants through fraccionation/destructiveprocesses sequences

Recovery of process water and organic solvents

Membrane

Ultrafiltration (UF)

Nanofiltration (NF)

Reverse Osmosis (RO)

Pure water

Monovalent salts

Small organic solutes

Divalent salts

Dissociated acids

Macromolecules

Microfiltration (MF)

Particles

Pressure Driven Membrane Processes

Case Studies

Dairy Industry

Coke Plant Waste Waters

Cork Processing Waste Waters

Dairy Industry

“Serpa” cheese by-products

Cheese whey (CW) from cheese production

Currently used ONLY in curd cheese production

Second cheese whey (SCW) from curd production

Currently WITHOUT further processing

Problem 1: low valorisation of an extremely rich product

Problem 2: Disposal of a strongly pollutant effluent and loss of

another valuable product

How to solve these two problems?

Possible solution: Development of an integrated process with

two major objectives

Objective One: Valorisation of “Serpa” cheese by-products.

Recovery of highly nutritive and valuable compounds

(Economic Advantage)

Objective Two: Wastewater minimization

(Environmental Advantage)

Proposed integrated process for by-products valorisation

and wastewater minimization

1 2 3UF

Product

3

4 5 6NF

Fines

CW (from

cheese

production)

SCW (from curd

production)

CW

without fines

SCW

without fines

Defatted SCW

Defatted

CW

Water, lactose,

salts and free

amino acids (a. a.)

Water, salts

(depurated

wastewater for

reuse, ex: CIP)

Legend:

1 & 4 – Removal of fines by filtration.

2 & 5 – Removal of fat by centrifugation.

3 & 6 – Ultrafiltration (3) and Nanofiltration (6)

Product1 – Protein concentrate.

Product 2 – Lactose concentrate, free a. a. and some

bivalent salts.Product 3 – Fat for butter production.

Product

1

Product

2

Fractionation of a feed stream (CW) containing

water, proteins, amino acids (a.a.), lactose and

salts

Production of a concentrate stream enriched in

proteins.

Production of a permeate stream enriched in

lactose, a.a., salts.

Objective of the Ultrafiltration unit operation:

Objective of the Nanofiltration unit operation:

Fractionation of a feed stream (SCW) containing essentially water, lactose and salts; but also some residual

proteins and amino acids (a.a.)

Production of a concentrate stream rich in organic matter.

Production of a permeate stream enriched in salts with low organic matter concentration.

Ultrafiltration (UF) & Nanofiltration (NF)

Important quantitative factors:

Permeation flux, Jp (related with process time)

Rejection coefficient, f (related with membrane selectivity)

f = (wA0 – wAp)/wA0

Pressure driven membrane separation process

Feed

wA0

Permeate

wAp

Concentrate

Nanofiltration

Experimental

Permeation experiments

Total Recirculation Mode

(for membrane selection and determination of best operating

pressure)

Concentration Mode

(with selected membrane and selected pressure)

Experimental

NF unit

Lab. Unit M20 from DSS A/S, Denmark

In all permation experiments: circulation flow rate = 9.2 L/min; T = 25ºC.

Second cheese whey characterisation

pH 6.2

Specific conductivity 23.3 mS/cm

Total Organic Carbon (TOC) 31.2 g C/l

Lactose 50.6 g/l

Total nitrogen by Kejdahl method 1.74 g N/l

Proteins and Free amino acids 8.3 g/l

Experimental

Characteristics of tested membranes

Membrane: HR-95-PP NFT50

Material Thin film composite on polypropylene

Thin film composite on polyester

PWP (kg H2O /m2 / hr/ bar) 3.0 6.5

Rejections (f) to reference solutes, % (Pressure=10 bar; T=25ºC) NaCl 97.3 69.0 Na2SO4 99.1 99.0 Glucose 98.5 94.5 Sacharose 98.6 98.5

Permeation Results - Total Recirculation Mode

0

10

20

30

40

50

60

70

80

0 10 20 30 40

Pressure (bar)

Per

mea

tio

n F

lux

(k

g/h

r/m

2)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 10 20 30 40

Pressure (bar)

f (T

OC

)

NFT50

HR-95-PP

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 10 20 30 40

Pressure(bar)

f (S

alts

)

NFT50

HR-95-PP

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 10 20 30 40

Pressure(bar)

f (N

itro

gen

)

NFT50

HR-95-PP

(b)(a)

(c) (d)

HR-95-PP

NFT50

PWP NFT50

PWP HR-95-PP

• important osmotic pressure

phenomena due to high

content of salts in SCW,

for HR-95-PP membrane

• high TOC (> 98%) and N

rejections (> 86%) for both

membranes

• low salt rejections for NFT50

and high salt rejections for

HR-95-PP

• higher productivities for

NFT50

• permeation fluxes vary

linearly with pressure

increase

Permeation Results - Total Recirculation Mode

0

10

20

30

40

50

60

70

80

0 10 20 30 40

Pressure (bar)

Per

mea

tio

n F

lux

(k

g/h

r/m

2)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 10 20 30 40

Pressure (bar)f

(TO

C)

NFT50

HR-95-PP

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 10 20 30 40

Pressure(bar)

f (S

alts

)

NFT50

HR-95-PP

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 10 20 30 40

Pressure(bar)

f (N

itro

gen

)

NFT50

HR-95-PP

(b)(a)

(c) (d)

HR-95-PP

NFT50

PWP NFT50

PWP HR-95-PPCONCLUSION

only NFT50 allows the feed

stream fractionation !

Selected membrane:

NFT50

Selected pressure:

Higher tested pressure

(30 bar)

Permeation Results - Concentration Mode

• Membrane: NFT50

Pressure: 30 bar

0

10

20

30

40

50

60

0 20 40 60 80 100

RR (%)

Per

mea

te F

lux

(k

g/h

r/m

2)

(a)

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

RR (%)

f (T

OC

)

(b)

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

RR (%)

f (N

itro

gen

)

(d)

0%

20%

40%

60%

80%

100%

0 20 40 60 80 100

RR (%)

f (S

alts

)

(c)

• Recovery Rate (RR) =

(Total permeate volume) /

Initial Feed volume) x 100%

•When RR :

f (TOC) and f (N) ~ constant

f (Salts) and flux

When the RR , the organic

matter / salts fractionation is

improved but the process

productivity falls

Permeation Results - Concentration Mode

TOC and Total Nitrogen concentrations in the concentrate

RR (% of water recovered)

TOC (g C/l) Total Nitrogen (g N/l)

Initial: 0 29.06 1.46 34.0 46.21 2.16 50.5 63.24 2.86 67.2 96.67 4.14 73.5 122.8 5.38 Final: 77.8 140.1 7.73

Conclusions - Total Recirculation

• The NFT50 membrane showed in a preliminary set of permeation experiments, the best results in terms of SCW fractionation and productivity.

• Optimal operation conditions: P of 30 bar, T of 25ºCand feed circulation flow rate of 9.2 l/min.

Conclusions – Concentration Mode

• The final concentrate stream is a lactose-enrichedsolution with a lactose conc. approx. 5 times higherthan the initial value Raw material forpharmaceutical, food or paper industries.

• SCW fractionation into a salt depleted lactoseconcentrate and a salt enriched permeate almost freefrom organic matter.

• The salt enriched permeate can be reused in the processor more easily disposed.

Fractionation of cheese whey/second cheese whey by Ultrafiltration, Nanofiltration and Reverse Osmosis leading to:

Recovery of products - protein concentrate, lactose and aminoacids, fat for butter production

Reuse of process water

Reduction of waste waters discharged

Conclusions

Coke Plant Waste Waters

The strategy for the treatment of ammoniacal wastewaters contaminatedwith priority pollutants:

• Ammoniacal wastewaters complex mixture fractionation (ammonia,phenols and cyanides) and confinement of the highly trace pollutantcompounds in separate streams for:

Application of specific treatments for the proprietary pollutantsconfined in the separated streams

Reduction of wastewater flow rate fed into the steam strippingcolumn

Treatment Strategy

OBJECTIVES

Fractionation by Nanofiltration of Ammoniacal

Wastewaters Contaminated with Phenol and Cyanides

Optimisation of an Integrated Process - Coupling

Nanofiltration (NF) with Steam Stripping for the

Treatment of Ammoniacal Wastewaters

Stripping Column Steam Savings

Integrated Process

NF

Destructive

Process

Cyanides

Phenols

Ammoniacal

Wastewaters

NH3

Stripping

Column

Destructive

Process

NH3, CN-

Phenols

Stripping

Column

Ammoniacal

Wastewaters

NH4+: 7.1-8.7 g/l

CN-: 75 – 276 mg/l

Phenols: 85-185 mg/l

Qcirc: 16 m3/h

NH4+: 0.004 -1.3 g/l

CN-: 7.4 – 9.6 mg/l

Phenols: 13-148 mg/l

Qcirc: 17.9 m3/h

Present Treatment Process Novel Treatment Process

Experimental Program

Wastewater Characterization

Nanofiltration of Ammoniacal Wastewaters

- Permeation experiments carried out in

concentration mode

Steam Stripping Modelling

Waste Water Physico-Chemical

Characterization

Parameter Value

TOC (mg C/l) 501.2

Conductivity (mS/cm) 27.3

Colour (Hazen unit) 248.6

pH 9.4

Ammonia (g/l) 7.1 - 8.7Phenol (mg/l) 85 - 151

Cyanide (mg/l) 85 - 185

High content in ammonia contaminated with phenol and cyanides

Nanofiltration Set-Up

Nanofiltration Membranes:

HR-98-PP (DSS)

Membrane Characterisation:

Hydraulic Permeability (Lp): Lp=2.99 kg/h/m2/bar

Solute rejections:

NaCl – 98%

Na2SO4 – 99.9% (Conc.= 0.002 M ,T= 25ºC, P= 30 bar, Qcirc.= 9.2 l/min.)

Lab Unit M20 (DSS)

Operating Conditions:

Membrane Surface Area (Am): 0.144 m2

Temperature (T): 25ºC

Pressure (P): 30 bar

Feed Circulation Flowrate (Qcirc.): 9.2 l/min

Water Recovery Rate (RR):

Rejection Coefficient (f):

Nanofiltration Set-Up

RRvolume of permeate

initial feed volume 100

feed

permeatefeed

C

CCf

NF

Permeate

Cpermeate

Concentrate

Feed Tank

Cfeed

Pump

Nanofiltration Permeation

Results

Variation of Permeate Flux with Water

Recovery Rate (RR)Operating conditions:T = 25ºC, P = 30 bar, Qcirc = 9.2 l/min

0

4

8

12

16

20

0 10 20 30 40 50 60

RR (%)

Per

mea

te F

lux (

kg/h

/m2)

Variation of NF Concentrate and

Permeate Streams Compositions with

Water Recovery Rate

Operating conditions T = 25ºC, P = 30 bar, Q = 9.2 l/min

RR 27% 39% 48% 53% C P C P C P C P

TOC (mg C/l) 599.5 108.0 623.5 91.4 801.0 79.5 891.1 97.8 Conductivity (mS/cm) 31.7 2.7 35.8 2.6 39.9 3.0 42.9 3.6 Colour (Hazen unit) 371.8 11.7 437.5 14.1 550.0 15.2 811.6 12.9

pH 9.2 10.3 9.0 10.2 8.9 10.2 8.8 10.1 Ammonium (g/l) 10.3 2.8 11.2 2.8 11.8 3.0 12.5 2.8

Phenol (mg/l) 205 10 225 14 217 <2 266 <2 Cyanide (mg/l) 23 180 20 60 44 12 40 0.6

• The cyanides maximal

removal occurs at

RR=40%

• Optimal fractionation of

ammonia-phenol/cyanides

at RR>40%

0

2

4

6

8

10

12

14

0% 10% 20% 30% 40% 50% 60%

TR

Co

nc.

(g

/l):

Am

ón

ia

0

50

100

150

200

250

300

350

400

Co

nc. (m

g/l): F

en

ol, C

ian

eto

RR

Am

mo

nia

Ph

eno

l, Cy

an

ides

Variation of the different components concentration

(ammonia, phenol and cyanides) with RR

Operating Conditions: T = 25ºC, P = 30 bar, Qcirc = 9.2 l/min

Variation of Rejection Coefficients with

Water Recovery Rate (RR)Operating conditions: T = 25ºC, P = 30 bar, Qcirc. = 9.2 l/min

Optimal Recovery Rate: RR = 39%

RR (%) f NH4+ f Phenol f CN-

27 73% 95% Negative (enrichement in the permeate 6.8 x)

39 75% 94%

48 75% 100% 73%

53 77% 100% 99%

Negative (enrichement in the permeate 2 x)

Steam Stripping Column

Column Characteristics

Height 13, 1 m Diameter 1,9 m Number of Plates (bubble cap) 20 Feed Inlet Plate Column Top Steam Inlet Column Bottom Steam temperature 110 °C Steam pressure 0.8 bar (relative pressure)

Steam Stripping Column

• Simulation using ASPEN

• Good agreement between experimental and calculated values

Feed stream Bottom Stream Bottom Stream (simulation) (experimental)

Flow rate (m³/h) 8.3 9.8 - Temperature 24 °C 99.6°C 87 °C PH 9.7 - 9.16 NH3 (mg/l) 14 500 135.7 130 CN- (mg/l) 320 14.9 15.3 Phenol (mg/l) 17.6 14.2 13.1 Steam (kg/h) 1600 - -

Integrated Process NF/Steam Stripping

NF: RR=40%, Pressure=30 bar, T=25ºC, Qcirc.=9.2 l/min

Ammoniacal

Wastewater

NH3

RR= 40%

Stripping Column

40% Steam Savings

Destructive

Process Destructive

Process

Cyanides

Phenols

NF

Economical Analysis:

Nanofiltration Investment cost/year (€/m3 perm.) 0.256

Operating cost/year (€/m3 perm) 0.427

NF Total Costs / year (€/m3 perm.) 0.683

Stripping Column

Steam Savings 136168 €/year

Integrated Process

Annual Savings 0.698 €/m3 effluent

Integrated Process NF/Steam Stripping

NF: RR=40%, Pressure=30 bar, T=25ºC, Qcirc.=9.2 l/min

0

5

10

15

20

25

30

35

40

0% 10% 20% 30% 40% 50% 60%

RR

Mem

b.

Are

a/e

fflu

ent

flo

wra

te

(m2/(

m3/h

))

24.8 m2/(m

3/h)

CONCLUSIONS

The ammonium/cyanide fractionation is optimal forthe nanofiltration water recovery rate of 40%

Maximal cyanide depletion from ammoniumconcentrate stream is achieved at a RR of 40%. Theconfinement of cyanide in the permeate stream allowsthe application of specific destructive treatment

The techno-economical analysis ofNanofiltration/Steam Stripping shows annual savingsof 0.698 €/(m3 of treated effluent) when the NFoperates at a 40% RR

Cork Industry

WASTEWATER

Process for softening and disinfection of cork planks generates highly polluted wastewaters

Immersion of cork planks in boiling water for 1 hour generates wastewaters rich in cork extracts -complex mixture of phenolic compounds - with UF fouling characteristics

OBJECTIVES Ultrafiltration Optimization: Membrane Permeation

Characteristics (Fluxes and Rejection Coefficients) andOperating Conditions

Removal of UF Fouling Agents in Cork ProcessingWastewaters Through the Integration of Flocculationand Flotation with UF

Optimization of Flocculation\Flotation\UF Operationfor Minimal UF Fouling

Experimental Program

Wastewater Characterization

Flocculation Optimization: Chitosan concentrationpH

DAF Optimization: Operating pressure

Recirculation Ratio: R\Q

Ultrafiltration Fouling Minimization for OptimalFlocculation\Flotation\UF Operation

Wastewaters Physico-Chemical

Characterization

Parameter Value

pH 4.9

TOC (mg C/L) 2469

Particle size (nm) 383.0

Total Polyphenols (g/L Galic acid) 0.958

Zeta potential (mV) -13.2

Reverse Phase HPLC ChromatogramColumn - Waters Nova-Pak C18

Wastewater Phenolic Solutes

COOH

OH

HO OH

Gallic acid

COOH

OH

HO H

Protocatechuic acid

COOH

OH

HH3CO

Vanillic acid Ferulic acid

OH

H3CO H

HC=CH-COOH

Ellagic acid

Hydrophilicity scale

Solutes Concentration (ppm)

Gallic acid 103.7

Protocatechuic acid 71.1

Vanillic acid 8.0

Ferulic acid 7.7

Ellagic acid 238.7

Membranes

Commercial Membrane: TS60 (Ropur)

Membrane Characterization

Operating conditions:

Temperature = 25ºC

Transmembrane Pressure = 2 bar

Feed flowrate = 200 L/h

Membrane surface area = 13.2 cm2

fC C

C

feed permeate

feed

Reference solutes: PEG,Dextran

0

1

2

3

4

5

0 10000 20000 30000 40000 50000

MW (Da)

log (

f/(1

-f))

MWCO

Ultrafiltration Set-Up

UF membranes Membrane surface area = 13.2 cm2

Operating conditions T = 25ºC, P = 1-3 bar, Qcirc. = 200 L/h

Flocculation

Colloid Water Characterization

Low pHs lead to higher particle sizes and to higher

zeta-potencials

pH Particle size zeta potential

(nm) (mV) Raw wastewater 4.9 383.0 -13.2

Clarified effluent: 2.9 763.0 -9.0 100 ppm Chitosan 4.0 379.6 -12.3

4.9 387.2 -13.6 Clarified effluent: 3.0 734.9 -4.7

200 ppm Chitosan 3.9 473.1 -10.6 4.9 426.3 -12.8

FlocculationOrganic Matter Removal

Optimal Operating conditions: 200 ppm chitosan

pH = 3

pH

TOC Total Polyphenols

TOC Removal

Total Poly. Removal

(mg C/l) (g/l galic acid) (%) (%)

Raw wastewater 4.9 2469 0.958 Clarified effluent: 2.9 2038 0.705 17% 26%

100 ppm Chitosan 4.0 2343 0.886 5% 8% 4.9 2386 0.910 3% 5% Clarified effluent: 3.0 1840 0.523 25% 45%

200 ppm Chitosan 3.9 2324 0.801 6% 16% 4.9 2371 0.865 4% 10%

Dissolved-Air-Flotation

SET-UP

Recirculation: R

Feed: Q

Clarified Wastewater

Flotation Unit

Operating Parameters:

Pressure: 4 and 5 bar

Recirculation ratio (R\Q): 0.19 – 0.85

Dissolved-Air-Flotation

Variation of TOC and Polyphenols Content with Pressure

and R\Q

R/Q TOC Total Polyphenols

(mg C/l) (g/l galic acid) Feed solution - 1840 0.523 5 bar (abs) 0.19 1501 0.441

0.48 1194 0.354 0.85 947 0.285 6 bar (abs) 0.19 1353 0.364 0.48 1177 0.311 0.85 946 0.262

R/Q TOC Removal (%)

Total Polyphenols Removal

(%)

5 bar (abs) 0.19 3 0 0.48 4 0 0.85 5 0 6 bar (abs) 0.19 12 17 0.48 5 12 0.85 5 7

Dissolved-Air-Flotation

Organic Matter Removal

Optimal Operating Conditions: R /Q = 0.19

Pressure = 6 bar (abs)

100Q

R1

C

C1Removal%

i

f

Phenolic acids RemovalFerulic and Ellagic acids

Ultrafiltration: TS60(T = 25ºC, P = 1 -3 bar, Qcirc = 200 L/h)

Membrane: TS60

0

1

2

3

4

5

6

7

8

0 1 2 3 4Pressure (bar)

Jv (

kg/h

/m2)

not treated

treated effluent

• Linear variation of permeate flux with pressure

• Enhancement of permeate fluxes in 60%

Ultrafiltration: CA1 (T = 25ºC, P = 1 - 3 bar, Qcirc = 200 L/h)

Membrane: CA1

0

5

10

15

20

25

30

0 1 2 3 4Pressure (bar)

Jv

(k

g/h

/m2

)

not treated

treated effluent

• Non-linear variation of permeate fluxes with pressure

• Enhancement of permeate fluxes in 30%

Ultrafiltration: CA2 (T = 25ºC, P = 1 - 3 bar, Qcirc = 200 L/h)

• Non-linear variation of permeate fluxes with pressure

• Enhancement of permeate fluxes in 130%

• Limiting Flux reached at 2.5 bar

Membrane: CA2

0

10

20

30

40

50

60

70

0 1 2 3 4Pressure (bar)

Jv

(kg

/h/m

2)

not treated

treated effluent

CONCLUSIONS

The flocculation removals of total polyphenols reach values inthe order of the 45% when 200 ppm of chitosan are added at apH of 3. The subsequent flotation operation raises the globalpolyphenols removal up to 62%.

The removal of the colloidal matter leads to the increase of the permeate fluxes, being this increase of 60% for the TS60 membrane, 30% for the CA1 membrane and 130% for the CA2 membrane.

CONCLUSIONS The membrane with higher MWCO, CA2, presented the

higher fouling in the treatment of the cork processingwastewater, displaying a limiting flux at a transmembranepressure of 2.0 bar.

Although the permeate flux increase, for the pre-treatedwastewater, was more pronounced for the CA2 membrane,it still presented a limiting flux at a pressure of 2.5 bar.

The performance of ultrafiltration cork processingwastewaters was highly improved by theflocculation/flotation pre-treatment.

REDE CYTED 311RT0438 - Recuperação de metais

por técnicas eletroquímicas e processos de

membranas para produção de materiais

nanoestruturados (RECMET).

The authors would like to thank Siderurgia Nacional

– Empresa de Serviços S.A. for their cooperation.

Miguel Minhalma would like to thank Fundação para

a Ciência e Tecnologia for the financial support.

Acknowledgements