Tzahi  Cath,  Carl  Lundin,  Jörg  Drewes    

Advanced  Water  Technology  Center  (AQWATEC)  Division  of  Environmental  Science  and  Engineering  

Colorado  School  of  Mines  Golden,  CO  

24th  Annual  WateReuse  Symposium    September  14th,  2009  

SeaJle,  WA  

A  Novel  Hybrid  Forward  Osmosis  Process  for  Drinking  Water  AugmentaQon  using  Impaired  Water  and  Saline  Water  Sources  

PresentaQon  Overview    The  Water-­‐Energy  nexus  

  Emergence  of  osmo5cally-­‐driven  membrane  processes  

  Poten5al  applica5ons  and  implementa5ons  

  Desalina5on  and  the  energy-­‐water  nexus  

  Osmo5c  dilu5on  of  seawater    

  AwwaRF  4150  

  Concluding  remarks  

The  Water  –  Energy  Nexus  Water to Energy…

Energy to Water…

Energy  Recovery  in  DesalinaQon  

http://www.energyrecovery.com/ http://www.ide-tech.com/Index.asp

OsmoQc  Pressure  as  an  Energy  Guzzler  

Seawater

membrane  

Δπ ≈ 350 psi

Conc. Seawater

(~50% rec.) Δπ ≈ 700 psi

OsmoQc  Pressure  as  an  Energy  Source  OsmoQcally-­‐driven  Membrane  Processes  

  Forward  osmosis  (wastewater  treatment,  pretreatment,  desalina5on)  

  Pressure  retarded  osmosis  (power  genera5on)  

Forward  Osmosis  (“engineered  osmosis”)  

Draw Solution

membrane  

Osmosis  

Brine / Draw

Solution

membrane  

OsmoQc  Pressure  as  an  Energy  Source  OsmoQcally-­‐driven  Membrane  Processes  

  Forward  osmosis  (wastewater  treatment,  pretreatment,  desalina5on)  

  Pressure  retarded  osmosis  (power  genera5on)  

Pressure  Retarded  Osmosis:    OsmoQc  Power  

From: R. J. Aaberg, Osmotic power - A new and powerful renewable energy source, ReFocus, 4 (2003) 48-50

Forward  Osmosis:  Draw  SoluQons  

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Osm

oQc  Pressure,  p

si  

Osm

oQc  Pressue,  atm

 

ConcentraQon,  M  

NH4HCO3  

NaCl  

CaCl2  

MgCl2  

KCl  

sucrose  

KNO3  

Forward  Osmosis:  Draw  SoluQons  

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oQc  Pressure,  p

si  

Osm

oQc  Pressue,  atm

 

ConcentraQon,  M  

NH4HCO3  

NaCl  

CaCl2  

MgCl2  

KCl  

sucrose  

KNO3  

State  of  Development  of  OsmoQcally-­‐driven  Membrane  Processes  

ApplicaQon  of  OsmoQcally-­‐driven  Membrane  Processes  

Aaberg (2003)

So…  what  are  the  advantages  and  limitaQons  of  osmoQcally-­‐driven  

membrane  processes?  

FO  vs.  RO  

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0   2   4   6   8   10  

Water  flux,  LMH  

Time,  Hours  

LFC-­‐1  RO  Mode  CA-­‐2  RO  Mode  CA-­‐2  FO  Mode  

Membrane cleaning

Holloway, R.W., Childress, A.E., Dennett, K.E., Cath, T.Y., “Forward osmosis for concentration of centrate from anaerobic digester”, Water Research, Vol. 41 (17), September 2007, 4005-4014.

Power  ConsumpQon    Rela5vely  good  economy  at  small  scale…  

  Economy  of  scale  holds  promise  for  successful  implementa5on  

Effect  of  Feed  Chemistry  on  FO  Process  Performance    Driving  force  decreases  when  recovery  increases  

  Good  rejec5on  of  contaminants  of  concern    

Cath et al., “Membrane Contactor Processes for Wastewater Reclamation in Space. Journal of Membrane Science, Vol. 257, (1-2), July 2005, 111-119.

Cartinella, Cath, et al. “Removal of Natural Steroid Hormones from Wastewater Using Membrane Contactor Processes”, Environmental Science and Technology, 40 (23), (2006) 7381-7386.

Jw  =  A  (ΔP  –  Δπ)  

FO

RO

Draw Solution tank

BW Brine

Concentrated BW Brine

What  are  the  LimitaQons?  The  Complexity  of  Mass  Transport  

Js  =  B  Δc  

Js,RO

  Unlike  RO,  FO  exhibits  bi-­‐direc5onal  diffusion  of  ions  

Jw  =  A  (ΔP  –  Δπ)  

How  can  we  simultaneously  reduce  energy  demand  in  SWRO,  protect  RO  membrane,  and  provide  mulQ  barrier  

treatment  of  impaired  water?  

Energy  Demand  of  DesalinaQon    High  energy  demand  of  SWRO  desalina5on  due  to  high  osmo5c  

pressure  of  the  brine  

Δπ

Additional flux

Decreasing Feed Conc.

Decreased Osmotic Pressure

Membrane

Solv

ent (

wat

er) F

lux,

J

RO  

ΔP  

FO  

The  beginning…  

T.Y. Cath, A.E. Childress, System and Methods for Forward Osmosis Assisted Desalination of Liquids, Patent Application No. 11/295,807, December 2005.

Water  Research  FoundaQon  (AwwaRF)  4150  Cath, T.Y., Drewes, J.E., Lundin, C. (2009). “A Novel Hybrid Forward Osmosis Process for Drinking Water Augmentation using Impaired Water and Saline Water Sources.” Draft Final Report. Awwa Research Foundation (AwwaRF #4150), Denver, Colorado.

FO/RO  Hybrid  for  Water  AugmentaQon:  OsmoQc  DiluQon  of  Seawater    Low  energy  desalina5on  /  enhanced  recovery  

  Dual  barrier  

Bench-­‐scale  TesQng  in  the  Lab    Bench  scale  forward  osmosis  system  

  Closed  loop  system    Doses  concentrated  salt  to  maintain  DS  concentra5on  

  SCADA  control  of  salt  dosing,  temperature,  and  data  acquisi5on  

Bench  Scale  Results:    Short  term  fouling  test  

  No  flux  decline  seen  in  short  term  secondary  effluent  experiments  

Conditions: 19ºC

1.5 LPM pH 7.5

Bench  Scale  Results:    OperaQng  Envelope  

Conditions: 19ºC

1.5 LPM pH 7.5

Feed Cond: SE: 850 µS/cm

DI: 80 µS/cm

Seawater

Pilot  TesQng  Temp. Control

RO Cell

Permeate

FO Cell

Feed (Recycled)

water

Waste

Seawater Draw

Solution

Pilot  Test  Results  Secondary  Effluent  Feed  

PC PC CC

Pilot  Test  Results  Secondary  Effluent  Feed  

Temp. Control

RO Cell

Permeate

FO Cell

Feed (Recycled)

water

Waste

Seawater Draw

Solution

FO Cell

Feed (Recycled)

water

Waste

Pilot  Test  Results  Secondary  Effluent  Feed  

Pilot  Scale  Results:  TerQary  effluent  feed  

Conditions: 2.4 LPM

pH 7.5 35 g/L Seawater

Feed Cond: TE: 850 µS/cm

Solute  Transport:  NH3,  NO3,  UV  

Conditions: 2.4 LPM

pH 7.5 35 g/L Seawater

Feed Cond: SE: 850 µS/cm

Ammonia rejection: FO: 75%, RO: 75%, Total: 94%

Solute  Transport:  NH3,  NO3,  UV  

Conditions: 2.4 LPM

pH 7.5 35 g/L Seawater

Feed Cond: SE: 850 µS/cm

Nitrate rejection: FO: 79%, RO: 82%, Total: 97%

Solute  Transport:  NH3,  NO3,  UV  

Conditions: 2.4 LPM

pH 7.5 35 g/L Seawater

Feed Cond: SE: 850 µS/cm

UV rejection: FO: 86%, RO: >99.9%, Total: >99.9%

Solute  Transport:  Micropollutants    Rejec5on  of  organic  micropollutants  

  Accumula5on  over  7-­‐day  experiment    Some  compounds  were  not  detected  in  feed  water  

  Clofibric  acid,  dichlorprop,  diclofenac,  fenofibrate,  gemfibrozil,  ibuprofen,  ketoprofen,  mecoprop,  naproxen,  salicylic  acid  

Compound Bench FO Pilot FO Pilot RO Pilot Total Diclofenac >99.9% 89% >99.9% >99.9% Gemfibrozil 80% 78% 78% 97% Ibuprofen n/a 87% 64% 93% Mecoprop 95% >99.9% - >99.9% Naproxen 90% 85% 94% 98% Salicylic Acid 72% >99.9% >99.9% >99.9%

Economic  Feasibility    Simple  model  

constructed  

  Helps  to  determine  the  level  of  recovery  of  impaired  water  possible  

Parameter Unit Value Finished water flow rate m3/day 100 Impaired water flow rate m3/day 200 Seawater TDS concentration g/L 35 Impaired water TDS

concentration g/L 0.5

RO recovery % 50 Energy cost $/kWh 0.20 Forward osmosis membrane

cost $/m2 45.00

Minimum return on investment ratio

1

Impaired water stream

Concentrated impaired water stream

Permeate (finished water)

RO reject stream

Reverse Osmosis

Forward Osmosis

RO influent stream

Seawater stream

Economic  Feasibility  

Economic  Feasibility  

Economic  Feasibility  

Concluding  Remarks  

  High  rejec5on  of  suspended  solids  and  macromolecules  and  rela5vely  high  rejec5on  of  most  dissolved  ions  and  molecules  

  Very  low  membrane  fouling  

  Low  energy  consump5on  and  energy  benefits  to  downstream  SWRO  

  Mul5  barrier  protec5on  leading  to  direct  potable  reuse  

  Preparing  for  a  large  scale  demonstra5on  project  

Acknowledgements  Funding Agencies

  Water Research Foundation (formerly AwwaRF)

  California Department of Water Resources

  National Aeronautics & Space Administration

  Russell Plakke and Brian Good, Denver Water

  Christiane Hoppe, Brandy Laudig, Ryan Holloway, Josh Cartinella, Dean Heil

  Edward Beaudry, Hydration Technologies Inc.

Thank  You