1. PLANNED POTABLE REUSE: URBAN WATER INSTITUTE’S SPRING WATER CONFERENCE
THE LAST FRONTIER
URBAN WATER INSTITUTE’S
SPRING WATER CONFERENCE
Palm Springs, California
February 8, 2017
George Tchobanoglous
Professor Emeritus
Department of Civil and Environmental Engineering
University of California, Davis

2. Paradigm shift in view of water What is potable reuse?
Discussion Topics
Paradigm shift in view of water
What is potable reuse?
Technologies for potable reuse
Cost and energy implications?
Where does potable reuse fit in the water portfolio
Driving forces for potable reuse
Sources of information
Closing thoughts

3. A PARADIGM SHIFT IN VIEW OF WATER
Wastewater is a renewable recoverable source of potable water, resources, and energy.

4. What Is Potable Reuse?
Current definitions for the different types of potable reuse
de facto indirect potable reuse (df-IPR)
Indirect potable reuse (IPR)
Direct potable reuse (DPR)
Proposed definitions for potable reuse

5. OVERVIEW: DE FACTO INDIRECT POTABLE REUSE
The downstream use of surface water as a source of drinking water that is subject to upstream wastewater discharges.
Courtesy City of San Diego

6. “Clean Water and How to Get It”
Allen Hazen (1914)
“Clean Water and How to Get It”
“Looking at the whole matter as one great engineering problem, it is clear and unmistakably better to purify the water supplies taken from rivers than to purify the sewage before it is discharged into them. It is very much cheaper to do it this way. The volume to be handled is less and the per million gallons the cost of purifying water is much less than the cost of purifying sewage.”

7. OVERVIEW: INDIRECT POTABLE REUSE
Typical injection well - OCWD
San Vicente reservoir, San Diego, CA

8. OVERVIEW: DIRECT POTABLE REUSE
DPR with Advanced Treated Water (ATW)
DPR with Finished Water

9. Proposed definitions for Potable reuse (After West Basin)
1. Groundwater Augmentation  (With six-month or greater retention time in an environmental buffer)
2. Surface Water Augmentation  (With six-month or greater retention time in an environmental buffer with an initial dilution of 100 to 1)
3. Raw Water Augmentation (Commingling with other raw sources followed by treatment in a water treatment facility)
4. Treated Water Augmentation (Finished water delivered directly into a treated water supply distribution system)

10. PICTORIAL VIEW OF POTABLE REUSE

11. Technologies for the Potable Reuse
TECHNOLOGY IS NOT A LIMITING CONSTRAINT!!

12. EXAMPLE OF TREATMENT PROCESSES for Potable Reuse: Orange County Water District AWTF
Adapted from OCWD

13. Microfiltration, Cartridge Filters, Reverse Osmosis, and Advanced Oxidation (UV) Technologies at OCWD
Microfiltration
Cartridge Filters
Reverse Osmosis
Advanced Oxidation

14. Decarbonator (CO2 Stripping)
DECARONATION AND LIME SATURATION AT OCWD
Decarbonator (CO2 Stripping)
Lime Saturator (pH adjustment)

15. What Does DPR Cost? Note: $/103 gal x 325.89 = $/AF
Data from original OCWD AWTF

16. DPR ENERGY USAGE Note: kWh/103 gal x 325.89 = kWh/AF
Data from original OCWD AWTF

17. where does potable reuse fit
IN The water Portfolio?
WATER SOURCES
Local surface water
Local groundwater (shallow and deep)
Imported water
Potable reuse (DPR and IPR, potential 20 to 40%)
Desalination (brackish and sea water)
Stormwater (?)
OTHER MEASURES
Centralized non-potable reuse (e.g., purple pipe)
Decentralized non-potable reuse (e.g.,greywater)
Conservation and curtailments

18. DRIVING FORCES FOR IPR AND DPR
The value of water will increase significantly in the future (and dramatically in some locations).
Population growth and global warming will lead to severe water shortages in many locations.
De facto indirect potable reuse is largely unregulated (e.g., secondary effluent, ag runoff, urban stormwater, highway runoff).
Infrastructure requirements limit most urban reuse opportunities (e.g., dual distribution systems).
Existing and new technologies can meet the water quality challenge to protect public health.
Stringent environmental regulations.

19. useful INFORMATION SOURCES FOR DPR
2015
2011
2014
2015
October 2016
POTABLE REUSE RESEARCH COMPILATION: SYNTHESIS OF FINDINGS
WE&RF PROJECT NO
December 2016

20. TAKE AWAY THOUGHTS
Ultimately, potable reuse is inevitable and will represent an essential element of a sustainable water future
Must think of wastewater differently
Must recognize technology is not an issue
Must recognize public is supportive
Must recognize that bold new planning is needed-now!!

21. THANK YOU
FOR LISTENING