ict-i presentation final

ICT I Desalination and Water Reuse

J. Georgiadis, O. Coronell, L. Rakocevic, P. Tontcheva, E. Morgenroth

“sea to sink to the sea again”

Desalination & Water Reuse• Institutions & PIs

– U.C. Berkeley: R. Shen – LLNL: O. Bakajin– Howard University: K. Jones – Notre Dame: P.

Bohn– University of Illinois: N. Aluru, D. Cahill, J. Economy, J.

Georgiadis, S. Granick, E. Luijten, B. Mariñas, J. Moore, E. Morgenroth, M. Shannon

– Massachusetts Institute of Technology: A. Mayes– Rutgers University: S. Prakash– University of Michigan: L. Raskin– Yale University: M. Elimelech

ICT-1: Organization & Objectives• Area I-A: Thermal Desalination and Liquid Discharge

Minimization– Reduce energy expenditure relative to RO– Minimize liquid discharge to less than 5% of total flux

• Area I-B: Pressure-driven and Active Membranes– Increase flux 2-fold– Decrease fouling

• Area I-C: Membrane Bioreactor Technology– Decrease sorptive, particle, and biofilm fouling– Link MBR with downstream processing (e.g. RO) for

water reuse

Reverse Osmosis Energy Use

Minimum energy of separation

John MacHarg and Randy Truby, “West coast researchers seek to demonstrate SWRO affordability”, Desalination and Water Reuse, 14/3, 2004.

Energetics of DesalinationP = + Preject + Ppolar + Pmembrane + Pviscous + Pfoul

Reverse Osmosis Cost

Shannon et al., “Science and technology for water purification in the coming decades”, Nature, 452, 2008.

ICT-1: Organization & Objectives• Area I-A: Thermal Desalination and Liquid

Discharge Minimization– Forward osmosis

• Area I-B: Pressure-driven and Active Membranes– Active membranes– NF/RO membranes– Antifouling membranes

• Area I-C: Membrane Bioreactor Technology– Fouling mechanisms– Extracellular polymeric substances

0

1

2

3

4

5

6

kW

h/m

3

MSF MED-TVC MED-LT RO FO-LT

Energy Requirements of Desalination Technologies

Contribution fromElectrical Power

Adapted from: McGinnis, Elimelech, “Energy Requirements of Ammonia–Carbon Dioxide Forward Osmosis Desalination”, Desalination, 207 (2007) 370-382.

RO FO

0 10 20 30 40 50 60 70 80 90 1000

50100150200250300350400450

(atm)

Recovery (%)

Seawater

Minimizing Liquid Discharge

Forward Osmosis (FO)R. McGinnis, D. Chen, O. Bakajin, M. Elimelech

Saline Water

Draw (NH3/CO2)

ProductWaterBrine

Membrane

Draw Solute Recovery

EnergyInput

D,b

Theo

Water flux

F,b

eff

Convection

Porous support

Active layer

Challenge: Concentration Polarization in FO

Concentrative external CP

Feed crossflow

Draw crossflow

Diffusion

Dilutive Internal CP

Diffusion

)(

)( ,,

effW

mFmDW

AJ

AJ

Active Transport Membranes

Active Transport - Nanocapillary Array Membranes S. Prakash, J. Lucido, H. Fitzhenry, J. Wan, G. Mensing, J. Georgiadis, M. Shannon

NCAM

HEMA

Au- NCAM

Ion transport occurs across membranes and AC bias is more effective than DC bias for manipulating ion flux.

0

40

80

120

160

0 25 50 75 100 125 150 175 200 225 250Time (min.)

Con

duct

ivity

(m

S)

0.00625 mM No bias1 mM No bias0.00625 mM DC bias1 mM DC bias0.00625 mM AC bias1 mM AC bias

Slope: 0.045 ± 0.001

Slope: -0.153 ± 0.001

Slope: 0.106 ± 0.002

Slope: -0.161 ± 0.004Slope: -0.231 ± 0.008

Slope: -0.295 ± 0.01



• Area I-B: Pressure-driven and Active Membranes– NF/RO membranes– Active membranes– Antifouling membranes


Water flux in Nanochannels L. Rakocevic, M. Suk, A. Raghunathan, N. Aluru, J. Georgiadis, M. Shannon

Water flux vs. ∆P for BNNT, CNT, and PMMA membrane

Flux enhancement in CNT/BNNT

Water transport by collective “hopping”events of single-file water molecules

Permeation coefficient, pn=k0 by reaction rate theory where k0 is equilibrium hopping rate

Density Functional TheoryLengthscale O(A)

Molecular DynamicsTimescale O(ns)

Lengthscale O(nm)

Coupled Poisson Nernst PlanckTimescale O(ms)

Lengthscale O(mm)

Ion mobility Diffusion coefficient

Partial charges

The system

The material

Characterization of RO MembranesO. Coronell, X. Zhang, D. Cahill, B. Mariñas

FT30 Reverse osmosis (RO)

Support Layer(Polysulfone)

Selective barrier(polyamide)

Membrane characterization procedures are needed

~150 nm

Polyamide (~100 nm)

NHCONH2 CONH NHCO

CONH COOH

Pressurized feed

Amine group

Carboxylic groupAmide link

Functional groups in the active layer

Polysulfone (50 mm)

Polyamide (~150 nm)

Ag+ Ag+ Ag+

Ag+

Ag+ Ag+

Ion probingRutherford backscattering spectrometry (RBS)

RBS DetectorHe+

pH

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Ion

prob

e co

ncen

tratio

n (M

)

0.0

0.1

0.2

0.3

0.4

0.5

R-COO- R-NH3

+

1. Quantification of functional groups (FGs)

FT30 (RO) RBS data

pH

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Ion

prob

e co

ncen

tratio

n (M

)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

w1 = 0.2 ; pKa,1 = 5.3

w2 = 0.8 ; pKa,2 = 9.0

Carboxylic groups

[R-COO-]MAX =

0.435 M

2. Modeling of ionization behavior of FGs

FT30 (RO) RBS data

3. Location of FGs in the active layer

Polyamide active layer

Polysulfone support layer

Chlorine

FT30 (RO) Secondary ion mass spectrometry (SIMS) data

~150 nm

1. Elemental composition of active layer2. Thickness and roughness of active layer3. Quantification of functional groups (FGs)4. Modeling of ionization behavior of FGs5. Quantification of steric and valence effects

on counterions6. Location of FGs in the active layer

Research achievements

Water Mobility in CNT MembranesL. Rakocevic (UIUC), J. Georgiadis (UIUC), O. Bakajin (LLNL)

∙ Thickness = 3 μm∙ Porosity = 2 %∙ Hydrophobic material∙ Average pore size=1.6nm∙ Atomically smooth walls

Double walled Carbon Nanotube

TEM image of CNT membrane

Holt et al. Science 2006

CNT Membrane Performance

MD: water diffusion coef. ~1.5×10-5 cm2/s ! Bulk water diffusion coef. ~ 2.6×10-5 cm2/sDiffusion inside CNTs has not been measured before

Energy requirements (estimated): Reduced Pmembrane 40% reduction relative to RO for seawater desalination

Experiment: Improved salt rejection and flux relative to commercial NF membranes

High water diffusion coefficient inside CNTs despite restricted space (~ nm)

Formasiero et al. PNAS 2008

Objectives

• Verify high (restricted) water diffusivity inside CNTs

• Measure water dispersivity inside CNTs• Quantify water displacement statistics

inside CNTs• Advance unique experimental technique

(MRI) for probing mass transport inside novel membranes

• Gradient G is applied for time δ

Diffusion-Weighted MRI (1)

Free waterBound water Bound water

20 30 40 50 60 70

G

00 Gx

Free water

wait for a short time ….

Bound water Bound water

xkxx x 00


Bound water Bound waterFree water

G

-20 -30 -40 -50 -60 -70

• Gradient –G is applied for time δ xGkGx s 01


Diffusion causes phase incoherence and therefore MRI signal loss

• The diffusion-weighted q-space (displacement space) gives a signal EΔ(q) such that:

• Example: 1-D Fickian diffusion

MRI signal:

Displacement-Weighted MRI

dRRqiRPqS )2exp(),()(

Propagator function – Probability that a spin will displace amount R (R = r’ – r) during time Δ

Accumulated phase term, where q = 1/(2π) γδg (g is the gradient amplitude)

)exp()( bDqS

Experimental setup and current progress

• 2% 20 % void fraction• 3 mm 100 mm-thick layerswith aligned carbon nanotubes

Experimental setup

LLNL current membrane fabrication improvements

Current ProgressSample with water

Sample with water +

CNT membrane parts

)exp()( bDbS



• Area I-B: Pressure-driven and Active Membranes– Active membranes– NF/RO membranes

– Antifouling membranes


PAN-g-PEO as an Additive for UF Fouling Resistance

Doctor Blade

Coagulation Bath

Casting Solution Heat Treatment

Bath

Casting Solution

Doctor Blade

Coagulation Bath

Heat Treatment

graft copolymer added to casting solution

segregate & self-organize at membrane surfaces

PEO brush PEO brush layer on layer on

surface and surface and inside pores inside pores

Fouling Fouling resistanceresistance

Asatekin, Kang, Elimelech, and Mayes: J.Membr.Sci. 298 (2007) 136-146. Kang, Asatekin, Mays, and Elimelech: J.Membr.Sci. 296 (2007) 42-50.

• Increased clean water flux with increased comb content

• After fouling with BSA - complete flux recovery with 20% comb content

Fouling Reversibility (with BSA)

Gray: Recovered flux after BSA fouling/water flushing

White: Pure water

Average AFM results are not consistent with observed fouling reversibility

-8

-6

-4

-2

0

2

4

F/R

(mN

/m)

PAN (P0-0) P50-5 P50-10 P50-20

Carboxylate-modified latex particle as model foulant

Membrane

Attractive interaction

Repulsive interaction

Comb content0% 5%

10%20%

• Incomplete flux recovery with 10% comb content • Average AFM results suggest repulsive interactions

PAN

-12 -10 -8 -6 -4 -2 00

15

30

45

60

Freq

uenc

y (%

)

F/R (mN/m)

PAN (P0-0)

Incomplete fouling reversibility due to heterogeneous comb distribution

PAN 5%

-12 -10 -8 -6 -4 -2 0 2 40

15

30

45

60

Freq

uenc

y (%

)

F/R (mN/m)

P50-5


Comb content

PAN 5% 10%


-1 0 1 2 30

15

30

45

60

Freq

uenc

y (%

)

F/R (mN/m)

P50-10

Comb content

PAN 5% 10% 20%


0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.50

15

30

45

60

Freq

uenc

y (%

)

F/R (mN/m)

P50-20

Comb content

10 100-1.0

-0.5

0.0

0.5

NaCl alone NaCl + CaCl

2

F/R

(mN

/m)

Ionic Strength (mM)

Fouling resistance due to steric interactions

• Interaction forces are independent of ionic strength– Electrostatic forces

cannot explain observed effects

– Steric interactions

Promising results using model foulants – but in MBR fouling mechanisms are more complex

• Model foulants– Proteins (BSA)– Polysaccharide (alginate)– Natural organic matter (humic acid)

• Fouling in MBR dominated by – Extracellular polymeric substances

(EPS)– Microbial flocs– Biofilm growth

Floc fragments Colloidal EPS Soluble EPS

Shear forces

Bacteria/archaeaEPS

Microbial floc

Membrane

Biofilm Growth

Organic substrate

Organic substrate

10 mM 30 mM 30 mM+Ca 100 mM0

300

600

900

1200

Cel

ls A

dher

ed (m

m-2)

PAN/PAN-g-PEO Commercial PAN

No E. coli Adhesion on PAN/PAN-g-PEO!

No attachment of E. coli cells on PAN-g-PEO membrane during static (1 h batch) adhesion test

Commercial membrane exhibited increased cell attachment as the ionic strength was increased

PAN-g-PEO UF membranes resistant against bacterial attachment

1 h

10 1000

25

50

75

90

100

PAN/PAN-g-PEO with NaCl With 1 mM Ca Commercial PAN with NaCl With 1 mM Ca

Rem

oval

(%)

Ionic strength (mM)

Percent removal of E. coli cells from the membrane at 150 cm/s cross flow velocity

Clean water rinsing can remove previously attached E. coli from PAN-g-PEO membrane

Relevance of MBR to Advanced Wastewater Reuse

DisinfectionDisinfection(UV )(UV )

Wastewater

MBRMBR using MF or UFusing MF or UF

ROROWater

suitable for reuse

• MBR: Microbial production and degradation of foulants (e.g., soluble extracellular polymeric substances - proteins, polysaccharides)

• RO: Fouling in RO (ICT1-B) is directly related to effectiveness of MBR treatment (ICT1-C)

• Disinfection: ICT III

Wastewater

Effects of long-term operation of MBR • Comparing short (hours) and long-term (weeks)

fouling in anaerobic MBR Petia Tontcheva

• Mixing and mechanical shear in MBR affects the microbial ecology

– Floc structure– Amount and characteristics of

extracellular polymeric substances (EPS)– Membrane fouling


Shear forces

Bacteria/archaeaEPS

Microbial floc

Membrane

Biofilm Growth

Organic substrate

Organic substrate

Short and long-term fouling in anaerobic membrane bioreactors

Petia Tontcheva (UIUC) PIs: Morgenroth (UIUC), Raskin (Michigan), Anne M. Mayes (MIT)

Background: Antifouling NF (PVDF-g-POEM) Membranes

• Dead-end filtration of activated sludge from MBR– PVDF-g-POEM NF: no flux loss over 16 h filtration – PVDF base: 55% irreversible flux loss after 4 h

0 120.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Nor

mal

ized

flux

Time (hours)

PVDF base (,)

PVDF-g-POEM (●,●)

Volatile suspended solids (VSS): ~1800 mg/L

Asatekin, Menniti, Kang, Elimelech, Morgenroth, Mayes: J.Membr.Sci. 285 (2006) 81-89.

How will the antifouling membranes perform in long-term experiments?

Time of cross-flow cell operation (d)0 5 10 15 20 25 30 35

Flux

(L/m

2 h)

0

20

40

60

80

100

120

Clean water flux of new membraneFlux with anaerobic biomassClean water flux after fouling

Long-term (30d) operation of PAN/PAN-g-PEO in anaerobic MBR

• Reduced flux due to cake layer formation

• Complete recovery of flux after clean water flushing

VSS: ~ 11, 000 mg/L

PES-V PES-O PVDF PAN-g-PEO/PAN

Irrev

ersi

ble

resi

stan

ce (1

0-12 m

)

-1

0

1

2

3

4

5Short-term (5 hrs)Long-term (13 d)Long-term (30 d)

The PAN/PAN-g-PEO membranes did not exhibit irreversible fouling

Membrane surface analysis by XPS

• No indication of inorganic fouling (no Ca, Mg, ... detected)• Increasing quantities of organic foulants on PES-O membranes during the long-

term tests

clean membraneShort-term Long-term

Ato

mic

ratio

0

20

40

60

80

100

120

(C+N)/SO/S

PES-O membrane

Functional group identification by ATR-FTIR

Wavenumbers (cm-1)

100015002000250030003500

Abs

orba

nce

0.00

0.02

0.04

0.06

0.08

0.10

Long-term (13 d) Short-term

O-HN-H C-H COOH

Amide I

C-O

Amide II

Irreversible foulants: proteins, carbohydrates, and humic acids

PES-O Membrane

Shear

High Shear

Low Shear

Solu

ble

EPS

•High shear results in–Smaller microbial flocs

–Less floc associated EPS

–Less soluble EPS

Influences microbial physiology to reduce microbial foulant (= EPS) production in MBR

Low shear

High shear

EPS from high shear MBR is stickier

• Continuous high shear produces less EPS in MBR - but EPS is stickier

• How to best operate MBR?• Mixing/shear main

contribution to energy input• Reduced fouling potential for

high shear operation• Variable shear can release

floc associated EPS and result in fouling

Membrane

CML COO-

COO -

COO -

EPS

- OOC

F

3 mm carboxylate modified latex particle

Membrane

CML COO-

COO -

COO -

EPS

- OOC

F

3 mm carboxylate modified latex particle

Extracellular polymeric substances (EPS) extracted from microbial flocs

Vision for integrated MBR for wastewater reuse

Wastewater

NF based MBRNF based MBRIntegrated application Integrated application

of sorptive, ion of sorptive, ion exchange, catalytic exchange, catalytic

mediamediaWater

suitable for reuseWastewater

• Single unit system without the need for downstream processing

• Increase membrane rejection (NF instead of UF or MF membrane)

• Integrate alternative removal mechanisms with biological process

ICT 1 Path forward

• Fundamental Science– Multiscale computational framework

to explain RO and active membrane systems

– Computational and experimental techniques to understand electrokinetic transport in single nanopores

– Novel optical, spectroscopic, AFM, and RBS techniques to understand transport in membrane systems

• Membrane materials– Improve robustness of novel

UF/NF/RO membranes (e.g. RSA, CNT, PAN-g-PEO, etc.)

– Develop appropriate membrane for forward osmosis desalination

– Long-term fouling and cleaning with novel fouling resistance membrane

• Biological processes– Link microbial ecology to fouling in MBR

• Mechanisms and characterization of microbial EPS production and degradation

• Microbial mechanisms of cell attachment and biofilm formation

– Removal of micropollutants (w/ SIEMENS)• Microbial conversion• Integrate sorptive or catalytic media with

microbial processes

• System integration– Demonstrate active membrane desalination– Complete pilot FO system– Apply magnetic resonance imaging (MRI) and

computational fluid dynamics (CFD) to reduce cake formation in MBR (w/ SIEMENS)

– Compare of aerobic and anaerobic MBR (w/ SIEMENS)


Shear

Bacteria/archaeaEPS

Microbial floc

Membrane


Shear

Bacteria/archaeaEPS

Microbial floc

Membrane

Biofilm GrowthBiofilm Growth

CNT-membrane

ict-i presentation final

Documents

extracellular

water reuse

objectives

siemens

ionic strength

functional

weighted mri

organization