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