Direct potable Reuse: A Path forward

1. Direct potable Reuse:A Path forward The Kappe Lecture Stevens Institute of Technology September 25, 2013 George Tchobanoglous Department of Civil and Environmental Engineering University of California, Davis

2. Overview of Presentation • Overview • Types of Projects • Driving Forces for Direct Potable Reuse • Trends on Treatment Technology • Overall System Management • Regulatory Requirements • Need for Common Accepted Vocabulary • Closing thoughts

3. Overview

4. How to Think About Wastewaterin the 21st Century Wastewater is a renewable recoverable source of energy, nutrients, and potable water

5. Types of Reuse Worldwide • Agricultural irrigation (seasonal demand) • Landscape irrigation (seasonal demand) • Industrial (constant demand, site specific) • Non-potable urban uses (limited volumes) • Recreation/environmental uses (site specific) • Indirect potable use through groundwater recharge (requires suitable aquifer) • Indirect potable use through surface water augmentation (availability of reservoir sites) • Direct potable use (best option, but public perception issues must be dealt with)

6. Reuse Market Size and Growth from 2008 Source: GWI Global Water Market 2008

7. Overview of Strategies for Potable Reuse

8. TYPES OF PROJECTS

9. Kraemer/Miller Spreading Basins, OCWDand Legacy Regulations

10. Barrier Injection Wells

11. Infiltration Basin, Florida, USA

13. Groundwater Injection Wells

14. Indirect Potable Reuse ThroughSurface Water Augmentation: San Diego, CA Courtesy City of San Diego

15. San Vincente Reservoir, San Diego County

16. DRIVING FORCES FOR DPR AND IPR

17. Driving Forces for DPR and IPR • The value of water will increase significantly in the future (and dramatically in some locations) • Sustainability - population growth along coasts • Global warming - severe water shortages • Opposition to inter basin water transfers • Limited alternative sources of water • Stringent environmental regulations • Environmental protection of aquatic species • Infrastructure requirements limit reuse opportunities • De facto indirect potable reuse is largely unregulated • Less expensive than other water supply options

18. Impact ofClimate Change on Areas Already Stressed -Increased orDecreasedFlowrates

19. Urbanization Along Coastal Areas • By 2030, 60 percent of world’s population will live near a coastal region • Withdrawing water from inland areas, transporting it to urban population centers, treating it, using it once, and discharging it to the coastal waters is unsustainable.

20. Impactof Urbanization on Agriculture Reuse

21. Impact of Coastal Population Demographicson Reuse, Hyperion WWTP, Los Angeles, CA

22. Factors Limiting Nonpotable and Indirect Potable Reuse Agricultural Irrigation • Large distance between reclaimed water and agricultural demand (e.g., energy for pumping) • Need to provide winter storage (expensive) Landscape Irrigation • Dispersed nature of landscape irrigation • Cost of parallel distribution system Indirect Potable Reuse • Most communities lack suitable hydrology for groundwater recharge • Availability of nearby suitable surface storage

23. Infrastructure Requirements Limit Reuse(Purple pipe may be a bad investment) Courtesy City of San Diego

24. De Facto Indirect Potable Reuseis a Well Established Practice (Regulated: secondary effluent (?): Unregulated:ag runoff, urban stormwater, highway runoff)

25. De Facto Indirect Potable Reuse Courtesy City of San Diego

26. TRENDS IN TREATMENT TECHNOLOGIES

27. OCWD Technology for Indirect and Direct Potable Reuse Adapted from OCWD

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

29. Reverse Osmosis ~ 20,000 m3/Bank

30. Decarbonator (CO2 Stripping) Orange County Water District, OCWD Lime Saturator (pH adjustment

31. Technologies for the Removal ofTrace Constituents and Unknowns Adapted from Sundaram et al., 2009

32. Comparison of Technologies for the Removal of Trace Constituents & Unknowns Adapted from Sundaram et al., 2009

33. Treatment Process Flow DiagramPure Cycle Corporation (c.a. late 1970s)

34. Treatment Process Flow DiagramPure Cycle Corporation (c.a. late 1970s)

35. Potential Future DPR Flow Diagrams

36. Existing and New Treatment Technologies • Technologies for the removal of BOD, TSS, nutrients, and pathogens • Technologies for the removal of TDS, trace constituents, and unknowns • Implement new treatment plant designs to produce water for potable reuse • Brine managementfor inland locations • TREATMENT IS NOT THE ISSUE

37. Overall System Management

38. Proposed DPR Strategy

39. Proven and Conceptual Engineered Buffer Systems

40. To Protect Public Health An engineered buffer can be used in place of an environmental buffer with greater control over water quality

41. Importance of Engineered Buffer: Impact of Low Molecular Weight Organic Compound)

42. Management Operational, and Technological Barriers

43. Impact of DPR on Future WWTP Design • Targeted Source Control Program • Modification of Raw Wastewater Characteristics • Elimination of Untreated Return Flows • Flow Equalization • Operational Mode for Biological Treatment (must design for different or multiple end points) • Improved Design and Monitoring • Ongoing Pilot Testing

44. In-Line and Off-Line EqualizationFor Enhanced Treatment Performance

45. Return FlowsTreatment, Flow Equalization, or Offsite Processing

46. A DPR CASE STUDY: SOUTHERN CALIFORNIA

47. Opportunities for the Future:The Southern California Example

48. ElectricPower Consumption for Urban Water Systems in Northern and Southern CA

49. Wastewater Management Infrastructure - Potential Locations for Water Plants OCWD type plant

50. Benefits of Southern California Example • Reliable alternative source of supply, more secure from natural disasters • Lower cost and reduced energy usage • More water available for agricultural use, especially during drought periods • Environmental benefits for bay delta habitat restoration