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Science and Technology for Sustainable Water Supply

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Title: Science and Technology for Sustainable Water Supply


1
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
2
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
3

International Water Management Institute
4
Regional and Temporal Water Scarcity
National Oceanic and Atmospheric Administration
5
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

6
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

7
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8
Wastewater Reuse
9
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
10
Reuse of Wastewater in Orange County, California
www.gwrsystem.com
11
GWR System for Advanced Water Purification
(Orange County)
Ultraviolet Light with H2O2
Microfiltration (MF)
Reverse Osmosis (RO)
OCSD Secondary WW Effluent
Recharge Basins
12
Namibia, Africa
13
Natural Beauty … but not Enough Water
14
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
15
The Treatment Scheme A Multiple Barrier Approach
16
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

17
Wastewater Reuse Membrane Bioreactor (MBR)-RO
System
Shannon, Bohn, Elimelech, Georgiadis, and Mayes,
Nature 452 (2008) 301-310.
18
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.
19
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.
20
AFM as a Tool to Optimize Copolymer for Fouling
Resistance
Kang, Asatekin, Mayes, Elimelech, Journal of
Membrane Science, 296 (2007) 42-50.
21
Wastewater Reuse Membrane Bioreactor (MBR)-RO
System
Shannon, Bohn, Elimelech, Georgiadis, and Mayes,
Nature 452 (2008) 301-310.
22
One Step NF-MBR System?
NF
23
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
24
Wastewater Reuse Osmotically-Driven Membrane
Processes
25
Wastewater Reclamation with Forward (Direct)
Osmosis
Wastewater
Concentrate Disposal
26
Osmotic MBR-RO Low Fouling, Multiple Barrier
Treatment
Achilli, Cath, Marchand, and Childress,
Desalination, 2009.
27
Reversible Fouling No Need for Chemical Cleaning
Mi and Elimelech, in preparation.
28
Desalination Reverse Osmosis
29
Population Density Near Coasts
30
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31
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32
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33
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

34
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)

35
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

36
Nanotechnology May Result in Breakthrough
Technologies
These nanotubes are so beautiful that they must
be useful for something. . ., Richard Smalley
(1943-2005).
37
Aligned Nanotubes as High Flux Membranes for
Desalination?
38
Research on Nanotube Based Membranes
Mauter and Elimelech, Environ. Sci. Technol., 42
(16), 5843-5859, 2008.
39
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?

40
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
41
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.
42
Desalination Forward Osmosis
43
The Ammonia-Carbon Dioxide Forward Osmosis
Desalination Process
Nature, 452, (2008) 260
McCutcheon, McGinnis, and Elimelech,
Desalination, 174 (2005) 1-11.
44
NH3/CO2 Draw Solution
NH4HCO3(aq)
(NH4)2CO3(aq)
NH4COONH2(aq)
45
High Water Recovery with FO
46
Energy Use by Desalination Technologies
(Equivalent Work)

McGinnis and Elimelech, Desalination, 207 (2007)
370-382.
47
Waste Heat
Geothermal Power
48
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

49
Acknowledgments
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