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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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Presentation on theme: "Science and Technology for Sustainable Water Supply Menachem Elimelech Department of Chemical Engineering Environmental Engineering Program Yale University."— Presentation transcript:

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 21 st Century, Yale University, April 21, 2009

2 1. Energy 2. Water 3. Food 4. Environment 5. Poverty 6. Terrorism and War 7. Disease 8. Education 9. Democracy 10. Population The Top 10 Global Challenges for the New Millennium 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

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8 Wastewater Reuse

9 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

10 Reuse of Wastewater in Orange County, California Prado Dam Santa Ana River Facilities Groundwater Replenishment System, GWR (70 MG/day)) www.gwrsystem.com

11 Ultraviolet Light with H 2 O 2 Microfiltration (MF) Reverse Osmosis (RO) OCSD Secondary WW OCSD Secondary WW Effluent Recharge Basins GWR System for Advanced Water Purification (Orange County)

12 Namibia, Africa

13 Natural Beauty … but not Enough Water

14 Windhoeks Solution: Wastewater Reclamation for Direct Potable Use 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 Goreangab Reclamation Plant (Windhoek)

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 Doctor Blade Coagulation Bath Casting Solution Heat Treatment Bath Casting Solution Doctor Blade Coagulation Bath Heat Treatment 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) Gray: recovered flux after fouling/cleaning (following physical cleaning (rinsing) with no chemicals) White: Pure water 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 base (, ) PVDF-g-POEM (,) 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

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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/m 3 50% recovery: 1 kWh/m 3

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? Hinds et al, Aligned multi-walled carbon nanotube membranes, Science, 303, 2004.

38 Research on Nanotube Based Membranes Mauter and Elimelech, Environ. Sci. Technol., 42 (16), 5843-5859, 2008.

39 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 purity Large scale production? Mauter and Elimelech, Environ. Sci. Technol., 42 (16), 5843-5859, 2008.

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 Shannon, Bohn, Elimelech, Georgiadis, and Mayes, Nature 452 (2008) 301-310. Minimum theoretical energy for desalination at 50% recovery: 1 kWh/m 3 Practical limitations: No less than 1.5 kWh/m 3 Achievable goal: 1.5 2 kWh/m 3

42 Desalination: Forward Osmosis

43 The Ammonia-Carbon Dioxide Forward Osmosis Desalination Process Energy Input Nature, 452, (2008) 260 McCutcheon, McGinnis, and Elimelech, Desalination, 174 (2005) 1-11.

44 NH 3 /CO 2 Draw Solution NH 3(g) CO 2(g) NH 4 HCO 3(aq) (NH 4 ) 2 CO 3(aq) NH 4 COONH 2(aq) HEAT NH 3(g) CO 2(g)

45 High Water Recovery with FO Seawater

46 Energy Use by Desalination Technologies (Equivalent Work) Contribution from Electrical Power 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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