Science and Technology for Sustainable Water Supply

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Science and Technology for Sustainable Water
Supply

• Menachem Elimelech
• Department of Chemical Engineering
• Environmental Engineering Program
• Yale University

Your Drinking Water Challenges and Solutions
for the 21st Century, Yale University, April 21,
2009
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The Top 10 Global Challenges for the New
Millennium

• Energy
• Water
• Food
• Environment
• Poverty
• Terrorism and War
• Disease
• Education
• Democracy
• Population

Richard E. Smalley, Nobel Laureate, Chemistry,
1996, MRS Bulletin, June 2005
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International Water Management Institute
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Regional and Temporal Water Scarcity
National Oceanic and Atmospheric Administration
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How Do We Increase the Amount of Water Available
to People?

• Water conservation, repair of infrastructure, and
  improved catchment and distribution systems ?
  improve use, not increasing supply!
• Increase water supplies to gain new waters can
  only be achieved by
• Reuse of wastewater
• Desalination of brackish and sea waters

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Many Opportunities

• We are far from the thermodynamic limits for
  separating unwanted species from water
• Traditional methods are chemically and
  energetically intensive, relatively expensive,
  and not suitable for most of the world
• New systems based on nanotechnology can
  dramatically alter the energy/water nexus

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Wastewater Reuse
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Reclaimed Wastewater in Singapore (NEWater)

• Source of water supply for commercial and
  industrial sectors (10 of water demand)
• 4 NEWater plants supplying 50 mgd of NEWater.
• Will meet 15 of water demand by 2011

5 miles
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Reuse of Wastewater in Orange County, California
www.gwrsystem.com
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GWR System for Advanced Water Purification
(Orange County)
Ultraviolet Light with H2O2
Microfiltration (MF)
Reverse Osmosis (RO)
OCSD Secondary WW Effluent
Recharge Basins
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Namibia, Africa
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Natural Beauty but not Enough Water
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Windhoeks Solution Wastewater Reclamation for
Direct Potable Use
Goreangab Reclamation Plant (Windhoek)
Water should not be judged by its history, but
by its quality. Dr. Lucas Van Vuuren National
Institute of Water Research, South Africa
The only wastewater reclamation plant in the
world for direct potable use
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The Treatment Scheme A Multiple Barrier Approach
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Most Important Public Acceptance and Trust in
the Quality of Water

• Breaking down the psychological barrier (the
  yuck factor) is not trivial
• Rigorous monitoring of water quality after every
  process step
• Final product water is thoroughly analyzed (data
  made available to public)
• The citizens of Windhoek have a genuine pride in
  the reality that their city leads the world in
  direct water reclamation

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Wastewater Reuse Membrane Bioreactor (MBR)-RO
System
Shannon, Bohn, Elimelech, Georgiadis, and Mayes,
Nature 452 (2008) 301-310.
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Fouling Resistant UF Membranes Comb (PAN-g-PEO)
Additives
amphiphilic copolymer added to casting solution
segregate self-organize at membrane surfaces
PEO brush layer on surface and inside pores
Fouling Resistance
Asatekin, Kang, Elimelech, Mayes, Journal of
Membrane Science, 298 (2007) 136-146.
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Fouling Reversibility (with Organic Matter)
White Pure water
Gray recovered flux after fouling/cleaning
(following physical cleaning (rinsing) with no
chemicals)
Shannon, Bohn, Elimelech, Georgiadis, and Mayes,
Nature 452 (2008) 301-310.
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AFM as a Tool to Optimize Copolymer for Fouling
Resistance
Kang, Asatekin, Mayes, Elimelech, Journal of
Membrane Science, 296 (2007) 42-50.
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Wastewater Reuse Membrane Bioreactor (MBR)-RO
System
Shannon, Bohn, Elimelech, Georgiadis, and Mayes,
Nature 452 (2008) 301-310.
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One Step NF-MBR System?
NF
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Antifouling NF Membranes for MBR (PVDF-g-POEM)

• 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

PVDF-g-POEM (?,?)
PVDF base (?,?)
Asatekin, Menniti, Kang, Elimelech, Morgenroth,
Mayes J. Membr. Sci. 285 (2006) 81-89
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Wastewater ReuseOsmotically-Driven Membrane
Processes
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Wastewater Reclamation with Forward (Direct)
Osmosis
Wastewater
Concentrate Disposal
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Osmotic MBR-RO Low Fouling, Multiple Barrier
Treatment
Achilli, Cath, Marchand, and Childress,
Desalination, 2009.
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Reversible Fouling No Need for Chemical Cleaning
Mi and Elimelech, in preparation.
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DesalinationReverse Osmosis
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Population Density Near Coasts
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Seawater Desalination

• Augmenting and diversifying water supply
• Reverse osmosis and thermal desalination (MSF and
  MED) are the current desalination technologies
• Energy intensive (cost and environmental impact)
• Reverse osmosis is currently the leading
  technology

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Reverse Osmosis

• Major improvements in the past 10 years
• Further improvements are likely to be incremental
  
• Recovery limited to 50
• Brine discharge (environmental concerns)
• Increased cost of pre-treatment
• Use prime (electric) energy ( 2.5 kWh per
  cubic meter of product water)

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Minimum Energy of Desalination

• Minimum energy needed to desalt water is
  independent of the technology or mechanism of
  desalination

• Minimum theoretical energy for desalination
• 0 recovery 0.7 kWh/m3
• 50 recovery 1 kWh/m3

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Nanotechnology May Result in Breakthrough
Technologies
These nanotubes are so beautiful that they must
be useful for something. . ., Richard Smalley
(1943-2005).
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Aligned Nanotubes as High Flux Membranes for
Desalination?
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Research on Nanotube Based Membranes
Mauter and Elimelech, Environ. Sci. Technol., 42
(16), 5843-5859, 2008.
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Next Generation Nanotube Membranes
Mauter and Elimelech, Environ. Sci. Technol., 42
(16), 5843-5859, 2008.

• Single-walled carbon nanotubes (SWNTs) with a
  pore size of 0.5 nm are critical for salt
  rejection
• Higher nanotube density and purity
• Large scale production?

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Bio-inspired High Flux Membranes for Desalination
Natural aquaporin proteins extracted from living
organisms can be incorporated into a lipid
bilayer membrane or a synthetic polymer matrix
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BUT . Energy is Needed Even for Membranes with
Infinite Permeability

• Minimum theoretical energy for desalination at
  50 recovery 1 kWh/m3
• Practical limitations No less than 1.5 kWh/m3
• Achievable goal 1.5 ? 2 kWh/m3

Shannon, Bohn, Elimelech, Georgiadis, and Mayes,
Nature 452 (2008) 301-310.
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DesalinationForward Osmosis
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The Ammonia-Carbon Dioxide Forward Osmosis
Desalination Process
Nature, 452, (2008) 260
McCutcheon, McGinnis, and Elimelech,
Desalination, 174 (2005) 1-11.
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NH3/CO2 Draw Solution
NH4HCO3(aq)
(NH4)2CO3(aq)
NH4COONH2(aq)
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High Water Recovery with FO
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Energy Use by Desalination Technologies
(Equivalent Work)

McGinnis and Elimelech, Desalination, 207 (2007)
370-382.
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Waste Heat
Geothermal Power
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Concluding Remarks

• We are far from the thermodynamic limits for
  separating unwanted species from water
• Nanotechnology and new materials can
  significantly advance water purification
  technologies
• Advancing the science of water purification can
  aid in the development of robust, cost-effective
  technologies appropriate for different regions of
  the world

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Acknowledgments