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 21 st Century”, Yale University, April 21, 2009
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Science and Technology for Sustainable Water Supply Menachem Elimelech Department of Chemical Engineering Environmental Engineering Program Yale University.
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Science and Technology for Sustainable Water Supply
Menachem ElimelechDepartment of Chemical EngineeringEnvironmental Engineering Program
Yale University
“Your Drinking Water: Challenges and Solutions for the 21st Century”, Yale University, April 21, 2009
1. Energy2. Water3. Food4. Environment5. Poverty6. Terrorism and War7. Disease8. Education9. Democracy10. Population
The “Top 10” Global Challenges for the New Millennium
Richard E. Smalley, Nobel Laureate, Chemistry, 1996, MRS Bulletin, June 2005
International Water Management Institute
Regional and Temporal Water Scarcity
National Oceanic and Atmospheric Administration
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
Many OpportunitiesWe 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
Wastewater Reuse
Reclaimed Wastewater in Singapore (NEWater)
5 miles
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
Reuse of Wastewater in Orange County, California
Prado Prado DamDam
Santa Ana River FacilitiesSanta Ana River Facilities
Wastewater Reuse: Membrane Bioreactor (MBR)-RO System
Shannon, Bohn, Elimelech, Georgiadis, and Mayes, Nature 452 (2008) 301-310.
One Step NF-MBR System?
NF
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
Mauter and Elimelech, Environ. Sci. Technol., 42 (16), 5843-5859, 2008.
Next Generation Nanotube Membranes
Single-walled carbon nanotubes (SWNTs) with a pore size of ~ 0.5 nm are critical for salt rejection Higher nanotube density and purityLarge scale production?
Mauter and Elimelech, Environ. Sci. Technol., 42 (16), 5843-5859, 2008.
Bio-inspired High Flux Membranes for DesalinationNatural aquaporin proteins extracted from living organisms can be incorporated into a lipid bilayer membrane or a synthetic polymer matrix
BUT …. Energy is Needed Even for Membranes with Infinite Permeability
Shannon, Bohn, Elimelech, Georgiadis, and Mayes, Nature 452 (2008) 301-310.
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
Desalination:Forward Osmosis
The Ammonia-Carbon Dioxide Forward Osmosis Desalination Process
EnergyInput
Nature, 452, (2008) 260
McCutcheon, McGinnis, and Elimelech, Desalination, 174 (2005) 1-11.
NH3/CO2 Draw Solution
NH3(g) CO2(g)
NH4HCO3(aq)
(NH4)2CO3(aq)
NH4COONH2(aq)
HEAT
NH3(g) CO2(g)
High Water Recovery with FO
RO FO
0 10 20 30 40 50 60 70 80 90 1000
50100150200250300350400450
(atm)
Recovery (%)
Seawater
0
1
2
3
4
5
6
kW
h/m
3
MSF MED-TVC MED-LT RO FO-LT
Energy Use by Desalination Technologies (Equivalent Work)
Contribution fromElectrical Power
McGinnis and Elimelech, Desalination, 207 (2007) 370-382.
Waste Heat Geothermal Power
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