95 TH Annual Conference | November 2015 | Raleigh Convention Center, Raleigh, NC

1. You Have Co-Digestion Now What? WERF Research Into the Operational Impacts of Co-Digestion 95TH Annual Conference | November 2015 | Raleigh Convention Center, Raleigh, NC

2. Acknowledgements • Lauren Fillmore – WERF • Lori Stone – LA Stone • Tim Muster – CSIRO • Hazen and Sawyer • Jared Hostetler • Wendell Khunjar • Irene Chu • Mike Bullard

3. Agenda • Why Energy Neutrality • Project Background • Survey Approach and Methodology • Survey Responses • Survey Results • Example Case Study • Q&A

4. Why Energy Neutrality

5. Just Ask Wally and Dilbert…

6. A New Paradigm Has Emerged EnergyReduce (as much as possible) NutrientsRecover (as much as possible) Clean WaterReuse (as much as possible)

7. Objective • Energy self sufficiency for wastewater treatment plants • Two pathways: • Reduction of energy consumption • Increase in energy capture • Anaerobic digestion a significant pathway for energy capture

8. Research Pathways For Energy Improvements

9. Co-Digestion Related Projects • Three interrelated projects • Hazen and Sawyer team • Carollo team • Kennedy-Jenks team • Combined goal to best account for the operational impacts of co-digestion • Hazen and Sawyer project focuses on a survey to document real world experiences with co-digestion

10. Project Background

11. Team Members • Principal Investigator: Matt Van Horne, Hazen and Sawyer • CSIRO • LA STONE LLC • Lori Stone • Other Partners • > 20 utilities confirmed for partnership (leveraging over $600,000 of previous work) • 2 university research programs

12. Tasks • Characterize the potential HSWs for co-digestion • Utility Survey • Database of substrates and operational knowledge • Identify/quantify co-digestion implications • Economic tool development (treatment, sidestream, biosolids, biogas) • Build on OWSO5R07 • Provide operational solutions • Identify key monitoring elements • Identify recommended preventative actions

13. Deliverables and Outcomes • Objective 1 • Database of survey results • To be shared among all 3 teams • Include utility partners from all teams and interested participants • Objective 2 • Economic assessment tool • 10 case studies • Objective 3 • List of key parameters • Compendium of corrective actions

14. Survey Methodology

15. Survey Question Flow A) Currently active program Specific general questions for each category to gauge availability of information and magnitude of program. B) Study completed, implementation forthcoming Question 1: General Demographics Question 2: What is the status of your co-digestion program? C) Study completed, implementation not forthcoming D) Future program possible, study(ies) not yet completed Option to continue into Phase 2 level of study or come back at a later time or be contacted by a research team member for “face to face” information transfer E) No program under consideration at this time

16. Current Status • Survey publicized on December 1, 2014 • Survey closed March 15, 2015 • Results were received globally • Analysis of responses • Case study identification • Economic tool development

17. Survey Responses

18. Phase 1 Survey Plus 2 anonymous submittals

19. Phase 2 Survey

20. Phase I Survey Results

21. Phase I Q11 – Program Status

22. Phase I Q12 – Type of HSW Collected *Percentage of 21 respondents who are actively co-digesting. “Other” wastes included glycerin and biodiesel.

23. Phase I Q15 – HSW addition to process

24. Phase I Q17 – Co-digestion drivers Minor impact Moderate impact No impact Strong impact

25. Phase I Q19 – Amount of HSW Collected in 2013 • Estimated Range of HSW Volume of 20 Respondents • 0.25 MG/year to 200 MG/year • Estimated Average of HSW Volume of 20 Respondents • 20 MG/year • Estimated Median of HSW Volume of 20 Respondents • 3.5 MG/year

26. Phase I Q21 – Types of Digestion • Of facilities that have co-digestion • 18 of 21 respondents use Mesophilic • 3 of 21 respondents use Thermophilic • Of facilities that do not have co-digestion • 1 of 4 respondents have no anaerobic digestion • 3 of 4 respondents use Mesophilic

27. Phase II Survey Results

28. Phase II Q8 – How Respondents Identified Acceptable HSW Streams • Of 10 respondents, all: • Had HSW locally availablein large quantities • Decided the waste would be easy to process and only cause minimal changes to the existing process • A vast majority of respondents: • Have a steady supply of HSW • Are already receiving HSW elsewhere • Bench/pilot tested with favorable results • Had nuisance HSW in the collection system

29. Phase II Q11 – Pilot Testing • Of 12 respondents: • 5 did run a pilot test before accepting waste • 7 did not run a pilot test before accepting waste • Of the respondents who did run a pilot test: • 3 are willing and able to share pilot test data/summary reports

30. Phase II Q15 – HSW Sourcing • Of 11 respondents: • 3 process HSW for free • 7 charge a tipping fee • 2 both accept HSW for free and charge a tipping fee • 1 accepts HSW for free with the intention of charging a tipping fee in the future • None pay for HSW

31. Phase II Q18 – HSW Sourcing *Others: “Both”, “Waste producers have nowhere else to go”

32. Phase II Q19 – HSW Sourcing *10 “No”, 2 “Yes”

33. Phase II Q27/28 – HSW Pretreatment *1 other: FOG aerobic pretreatment

34. Phase II Q63 – Digester Loading *1 other: proprietary software

35. Phase II Q67 – Volatile Solids Reduction

36. Phase II Q72 – Enhanced VSR Reduction • Only 3 of 8 respondents said “Yes”

37. Phase II Q73 – Enhanced Digester Gas Production • 8 of 9 respondents said, “Yes” • Reported gas increases ranged from 15% to over 300%

38. Phase II – Effects of Co-digestion • 9 of 9 respondents said that co-digestion had no effect on the quality or quantity of centrate from the dewatering facility • 9 of 9 respondents said that co-digestion had no effect on dewatering • 7 of 8 respondents said that co-digestion had no effect on the biosolids quantity or quality produced; the other 1 respondent said that co-digestion enhanced the biosolids quality

39. Phase II – Operation & Maintenance

40. Phase II – Operation & Maintenance

41. Phase II – Operation & Maintenance

42. Phase II Q87 – Odor Control Changes

43. Phase II Q89 – Receiving & Pretreatment

44. Phase II Q90 – Receiving & Pretreatment

45. Phase II Q91 – Receiving & Pretreatment

46. Example Co-Digestion Case StudyF. Wayne Hill WRF, Gwinnett County, GA

47. F. Wayne Hill, System Overview • Placed in service in January 2012 • Receives up to 30,000 gpd of pre-screened grease trap waste and sugar processing waste

48. Overview of Receiving and Pretreatment Access controlled by keypad Records delivery, flow & pH to billing system Integral grinder and rock trap (overwhelmed by high debris loads) Hauler offload by pressurizing tanks (no wear /tear on unloading pump)

49. Tank Configuration 4 tanks- 20,000 gallons/ea Insulated and jacketed Radar level sensor on top Pressure level sensor at bottom Access for cleaning and to top of tank

50. Summary Findings • Limit or preheat any kind of pretreatment • High debris loads are a problem – need separate rock trap • Haulers using air assist offloading works well • Concentric tube heat exchangers are effective and appear to not be a maintenance issue (over initial duration) • Hose pumps not recommended • Do NOT feed grease upstream of digester heat exchangers • Integrated odor control works for Gwinnett County