Re-inventing the Nation’s Urban Water Infrastructure [ReNUWIt]
Energy-efficient Wastewater Reuse
Richard G. Luthy, Stanford University and the ReNUWIt Team
Main messages
• Recycling & energy recovery – Decentralized systems
– New technologies
– Efficient desalination
• Demonstrate at test-bed scale – Assess reliability & control
– Gain acceptance
• Systems-level analysis – Savings & cost analysis
– Scale-up & build out
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Frank Gehrke (chief of snow surveys) and Gov. Jerry Brown “Measuring” the Sierra snowpack on April 1, 2015 First time that there was no snow to measure
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Urban systems for water supply resiliency & energy efficiency
Water In
Water Treatment
Resource Recovery
Water Out
potable sewage
runoff
potable
non-potable
Managed Surface Water
Managed Aquifer
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Decentralized water reclamation
• “Satellite” treatment plants
• Working together with centralized treatment
• Hybrid operations for greatest efficiencies
Lee et al., Environ. Sci. & Tech., 47(19), 2013 NSF-EPA-DOE wksp 4/28/15 5
Decentralized water reclamation
• Avoid pumping water back up hill and save energy
• Avoid cost of reverse pipeline
• Reclaim the water where it’s generated and needed
4-5 miles and 100-120 ft up hill
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Decentralized water reclamation
• Avoid salt water intrusion
• There’s less salt further up in the system
• Less risk of salt build up in soils
Brackish water intrusion hot spots
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Decentralized water reclamation
•Stanford wastewater at Serra Street approx.
360 ppm salt •Palo Alto recycled water approx. 770 ppm salt •Stanford wastewater best for irrigation & long-term salt management
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New technologies & water reuse
• Recover energy & water from treatment using new technologies
• Convert organic matter to methane & electricity
• Avoid energy-intensive aeration
Palo Alto Regional Water Quality Control Plant
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Innovative water reclamation: Recover energy from carbon & nitrogen
• Recovery energy using new technologies
1.7 kW-h/m3
0.3 kW-h/m3
From combustion of reduced carbon (organics)
From combustion of reduced nitrogen (ammonia)
2 kW-h/m3 potential to reclaim water & energy
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Recovery of energy from carbon & nitrogen
organic carbon
CH4 CO2 Energy
recovery
Staged anaerobic fluidized
bed membrane bioreactor
NH4+ N2O N2
Energy recovery
Coupled aerobic-anoxic nitrous decomposition
operation
Innovative water reclamation:
“Green energy” because it’s from biomass not fossil fuels
Question
• Can we treat municipal wastewater 100% anaerobically to achieve net energy production while meeting effluent quality standards, and at lower cost than by conventional aerobic treatment ?
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Staged Anaerobic Fluidized MBR (SAF-MBR)
Kim et al., Environ. Science & Technology, 45:576(2011)
Influent
TCOD
523
mg/L
Recycle
Permeate
Effluent
TCOD
60
mg/L
GAC Particles
First Stage Second Stage
with membrane
Influent
Methane Methane
Recycle
Effluent
Permeate
05
1015202530354045
0 100 200 300 400 500
mg
/L
Day of Operation
SAF-MBR Effluent BOD5
} Temp. Range oC
Shin et al., Bioresource Technology, 159, 95-103 (2014)
20- 15
14- 8
15- 25
26- 32
25- 14
13- 09
USA EPA Upper Limit
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Biosoids Production
0.05 kg VSS/kg COD and
already digested and
less than half that from aerobic
treatment
Shin et al., Bioresource Technology, 159, 95-103 (2014)
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Superior removal of pharmaceuticals: new anaerobic system vs aerobic system
SAF-MBR at Stanford McCurry et al., Environ. Sci. & Technol. Letters, 1:459, 2014
Innovative water reclamation
Scale of Wastewater Treatment
• Lab scale: gal/day
• Pilot-scale: 1-10 gal/min
• Full scale: 10-100 gal/second
Pilot-scale is also practical for decentralized or satellite applications
This size is believable!
Innovative water reclamation
Codiga Resource Recovery Center
Pilot-scale test bed facility
Wastewater and Waste Organics
Reclaimed Water with
Energy Savings
Construction started April 20, 2015
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50 mgd, Carlsbad, CA Poseidon San Diego County Water Authority
Seawater desalination
8 mgd, San Jose, CA Silicon Valley Adv. Water Purification Fac.
Santa Clara Valley Water District
Wastewater desalination
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Input ≈ 0.3
kWh/m3
Input 1.7 kWh/m3
Fresh water recovery
-1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
Input ≈ 3.5 kWh/m3
Seawater Wastewater Future
Salt
Removal
Salt
Remova
l
Nitrogen
Organic
Remova
l
Energy used
or produced
(kWh/m3)
Salt
Remova
l
Current
Organic
Nitrogen
Fresh water @
very low energy
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22
Cost comparison of water supplies
Source: LADWP 2010 Urban Water Management Plan and Water Resources Division NSF-EPA-DOE wksp 4/28/15 22
Food-energy-water nexus Salinas/Monterey/Watsonville
• Case study
• Not part of the State Water Project
• No imported water
• Three growing seasons/year
• Nutrient-rich muni. wastewater
• All-year water supply
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Monterey County Water
Recycling Project Recycled
Water Plant
Irrigated land &
salt water barrier
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Monterey Water Reclamation Plant
SAF-MBR Footprint
Google - 2014 NSF-EPA-DOE wksp 4/28/15 25
Take-home messages
• Recycling & energy recovery – Decentralized & new technologies
– Efficient desalination
• Demonstrate at test-bed scale – Assess reliability & control
– Gain acceptance
• Systems-level analysis – Savings & cost analysis
– Scale-up & build out
• Food-energy-water nexus NSF-EPA-DOE wksp 4/28/15 26