Julian Sandino, PhD, PE, BCEE IWA & WEF Fellow

Julian Sandino, PhD, PE, BCEE IWA & WEF Fellow

VCS Denmark Mads Leth Per Henrik Nielsen Carsten Steen Soren Eriksen Niels M. Askjær CH2MHILL Dru Whitlock Tom Johnson Tim Constantine Dwight Houweling

Nitrification increases O 2 demand Longer sludge age during low temperature increases biomass endogenous demand and larger aeration volume also requires additional mixing NH 3 -N conversion to NO 3 -N typically doubles O 2 demand Denitrification only partially recovers O 2 Unaerated zones for Bio P and Denitrification require mixing energy Low Nutrient requirements could require filtration (extra pumping?)

Effective primary treatment reduces carbon load to subsequent BNR basins, while increasing potential for energy recovery from sludge Carbon needs for denitrification and P-removal must be addressed (external carbon? WAS fermentation/hydrolysis?) Carbon present in sludge offers opportunity for significant energy recovery : CHP Cogeneration

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

ø 385,000 PE BNR facility 76% energy self-sufficient in 2011

Contribute towards achieving VCS s corporate goal of energy self-sufficiency and carbon neutrality by 2014. Identify energy optimization opportunities (EOOs): concentrate on short-term, readily implementable scenarios to reduce consumption and/or increase generation, decreasing GHG emmissions Identify and document all options, including longer term opportunities for positive net energy status for future consideration

Ejby Mølle WWTP 2011 Annual Average Electricity Consumption Anaerobic Digestion 3.83% Sludge Storage 1.56% Thickening/Dewatering Screen, Grit, and Grease Centrifuges 3.88% 6.44% Other 5.59% Primary Treatment 3.09% Pumping to Trickling Filters 2.15% Pumping to Activated Sludge 5.80% Activated Sludge - Other 0.24% Activated Sludge - WAS Pumping 0.22% Activated Sludge - RAS Pumping 0.86% Activated Sludge - Oxidation Ditch Mixing 2.09% Effluent Filters 10.43% Activated Sludge - Oxidation Ditch Aeration 39.35% Trickling Filters - Stage 2 pumping 7.30% Trickling Filters - Recirculation pumping 4.73% Trickling Filters - WAS/Humus Pumping 0.01% Trickling Filters - Return Pumping to Act Sludge 0.64% Activated Sludge - Anaerobic Zone Mixers 1.78%

Adopted screening criteria Readily implementable; Primarily process modifications Significant impact on energy profile; Proven elsewhere Short-listed EOOs Implement chemical enhanced primary treatment (CEPT) Operate at shorter BNR system solids retention time (SRT) Decommission TFs and convert TF clarifiers to CEPT for wet weather treatment Reduce effluent filtration operation to 12 hours per day Longer term Improvements for positive net energy status Co-digestion of high strength waste by mid 2014 Implement deammonification for N removal in sidestreams by 2014; mainstream by 2015 Replace oxidation ditch mechanical aerators with fine bubble diffused aeration

Energy Produced 2011 Additional Energy Produced Additional Energy Saved All Operational EOOs + Anammox + Diffusers All Operational EOOs Chemically Enhanced Primary Treatment Partial Effluent Filtration Lower Bioreactor Sludge Age No Trickling Filters Energy Self-Sufficiency Existing Condition (Baseline) 75% 80% 85% 90% 95% 100% 105% 110% 115% 120%

2009 2010 2011 2012 2013 2014 2009 2010 2011 2012 2013 2014 9,000,000 8,000,000 7,000,000 6,000,000 5,000,000 4,000,000 3,000,000 2,000,000 1,000,000 kwh/year - Electrical Energy Production Usage 25,000,000 20,000,000 15,000,000 10,000,000 Production Usage Electrical + Heat Energy 5,000,000 kwh/year -

Full-scale evaluation of co-digestion with organic waste Implementing sidestream and mainstream deammonification for N control Developing hybrid aeration concept by combining mechanical and diffused aeration systems

High-strength waste increases biogas generation Co-digestion in Anaerobic digesters Energy Recovery from cogeneration (heat and electrical)

Sidestream deammonification Mainstream hydrocyclones

Plant-wide mass and energy balance model used to evaluate operational and facility energy optimization scenarios Collaborative approach identified operational path to energy selfsufficiency Co-digestion and deammonification (sidestream and mainstream) capabilities will yield positive net energy status by end of 2014 VCS is well into achieving adopted goal of achieving energy and CO 2 neutrality VCS & CH2MHILL and Project Team Project received 2013 WEX Process Optimization award