Achieving Net Positive Energy Can Be Closer Than You Think: The Ejby Mølle WWTP Story

1. Achieving Net Positive Energy Can Be Closer Than You Think: The Ejby Mølle WWTP Story Tom Johnson, PE NCAWWA/WEA 2013

2. VandCenterSyd (VCS) Courtesy of Google Maps (Altered by CH2MHILL) Established in 1853 as first modern waterworks in Denmark 3rd large water and wastewater company in Denmark. HQ in Odense. Operates 7 WTPs and 8 WWTPs with 2,125 miles (3,400 km) of conveyance

3. Ejby Mølle WWTP Optimization Project • Achieving Energy Self-Sufficiency through process optimization • Contribute towards achieving VCS’s goal of energy self-sufficiency by 2014. • Identify energy optimization opportunities (EOOs) • concentrate on short-term, readily implementable actions • Reduce energy consumption and/or Increase energy generation. • Identify and document all options, including longer term opportunities.

4. Ejby Mølle WWTP • 385,000 PE (~15 mgd) BNR facility • Currently treating about 10 mgd • 76% energy self-sufficiency in 2011

5. Ejby Mølle WWTP

6. Detailed Energy Consumption Data Available for Analysis

7. Full Plant Mass/Energy Balance Developed Calibrated using 2 years of historical data

8. A Workshop helped identified several energy optimization opportunities A long-list of 35 potential EOOs was defined Treatment Process Modifications (18) Equipment Improvements (8) Energy Generation Improvements (9)

9. Use of process model and screening criteria lead to a short-list in a workshop setting • Adopted screening criteria: • Readily implementable; Primarily process modifications • Significant impact on energy profile; Proven elsewhere • Short Listed EOOs: • Implement chemical enhanced primary treatment (CEPT) • Nitrify centrate in trickling filters (TFs) • Decommission TF and convert TF clarifiers to CEPT for wet weather treatment • Operate at shorter BNR system SRT • Reduce effluent filtration operation to 12 hours per day

10. Reviewed Longer Term Options • Some other options evaluated… • Convert existing centrate holding to Anammox treatment • Replace oxidation ditch mechanical aerators with fine bubble diffusers and blowers • VCS notified that the Dalum Paper Mill would cease production at the end of 2012.

11. Summary of Operational EOO Results

12. Summary of Operational EOO Combinations

13. Summary of Facility Improvement EOO Results

14. Ejby Mølle WWTP – Achieving Energy Self-Sufficiency Through Process Optimization

15. Summary and Conclusions Plant-wide mass and energy balance model used to evaluate operational and facility energy optimization scenarios Collaborative approach resulted in identifying a path to energy self-sufficiency Potential options for net energy positive condition indentified VCS is well into achieving adopted goal of achieving energy and CO2 neutrality

16. What’s been done and what’s next? • Lowered SRT • Relocate chemical feed for CEPT • Pilot tested co-digestion with different local wastes • Evaluated ANAMMOX sidestream treatment processes/vendors • Looked at strategies for future liquid stream ANAMMOX integration • Full diffuser evaluation

17. How’s it going? Net Positive for 2 months via lower sludge age.

18. How’s it going? Winter + Loss of Papermill. Long time for WWTP to adjust

19. How’s it going? Process Stabilizes. Up to 85-92% Self Sufficiency

20. How’s it going? July (78%): Rebuilt Transformer and ICE Electrical Boards. Lost at least 4 days of generation.

21. How’s it going? August (53%): ICE out of 2 weeks due to repairs and maintenance. New motor on order (October)

22. Project Team CH2MHILL Julian S. Dru W. Tom J Ramboll Michael N. VCS Mads L. Per Henrik N. Lise H. Christian A. Soren E. Bjarne C. Carsten S. Ib P. Arne M.

23. Ejby Molle WWTP Optimization Project • Questions? 2013 WEX Global Water and Energy Innovation Award Winner