NC AWWA-WEA 93rd Annual Conference November 12, 2013 Tim Woody Resource Recovery Division Director, City of Raleigh Jonathan Treadway P.E, BCEE, CDM Smith TAKE 2 – BIOSOLIDS STRATEGY MODIFICATIONS FOR THE CITY OF RALEIGH TO TAKE ADVANTAGE OF TECHNOLOGY ADVANCEMENTS 1

NC AWWA-WEA 93 rd Annual Conference Presentation Outline 1.Project Background and Objectives 2.Biosolids Management Alternatives 3.Selected Project Direction 4.Implementation Plan 5.Conclusion 2 TW

NC AWWA-WEA 93 rd Annual Conference City of Raleigh provides wastewater service to nearly 500,000 people Neuse River WWTP – 44 mgd average Smith Creek WWTP – 1.2 mgd Little Creek WWTP – 0.7 mgd average 3 TW

NC AWWA-WEA 93 rd Annual Conference Goals for Master Plan Update Identify financially feasible management strategy Demonstrate cost-effectiveness compared to the “base case” Update 2008 Biosolids Master Plan with new technologies Account for changing conditions Advance the goals of the City’s EMS program for biosolids TW

NC AWWA-WEA 93 rd Annual Conference Changing Conditions Driving Update TW

NC AWWA-WEA 93 rd Annual Conference Changing Conditions Driving Update TW

NC AWWA-WEA 93 rd Annual Conference Overview of Management Strategies Considered AlternativeManagement Strategy 1Base Case* 2Anaerobic Digestion + Solar Drying 3Thermal Hydrolysis + Anaerobic Digestion + Solar Drying * Base case includes diversified outlets: Alkaline stabilized Class A product (Raleigh-Plus) Third party composting Aerobically digested Class B product Landfill JT

NC AWWA-WEA 93 rd Annual Conference Management Strategies Alt. 1 - Base Case (Aerobic Digestion) 7 DT/day 57 DT/day JT

NC AWWA-WEA 93 rd Annual Conference Management Strategies Alt. 2 - Anaerobic Digestion + Solar Drying 9 40 DT/day New Facilities Include: New GBT Building Three An. Digesters (2.75 MG each) Biogas Storage Upgraded Dewatering 16 Solar Dryers JT

NC AWWA-WEA 93 rd Annual Conference Management Strategies Alt. 3- Thermal Hydrolysis + Anaerobic Digestion + Solar Drying 10 JT New Facilities Include: Pre-screening and Pre-dewatering Thermal Hydrolysis Equipment Two An. Digesters (1.6 MG each) Upgraded Dewatering Biogas Storage 8 Solar Dryers 32 DT/day

NC AWWA-WEA 93 rd Annual Conference 11 JT

NC AWWA-WEA 93 rd Annual Conference Comparison of Alternatives - 20 year net present worth Alt. No. DescriptionCapital Cost ($M) O&M Cost ($M) Total Cost ($M) 2008 An. Digestion + Thermal Drying $153.4$43.6$ Base Case$ 28.3$82.1$ An. Digestion + Solar Drying $ 97.5$ 34.1$ Thermal Hydrolysis + An. Digestion + Solar Drying $ 81.2$ 27.6$ JT

NC AWWA-WEA 93 rd Annual Conference Evaluation Criteria and Summary of Results Alt. No. DescriptionNet Present Value of Costs ($M) O&M Cost per Dry Ton Non- Cost Criteria Greenhous e Gas Off- Set (metric ton CO 2 /yr) 1Base Case$110.4 $23758%1,000 2An. Digestion + Solar Drying$131.6 $14483%5,000 3 Thermal Hydrolysis + An. Digestion + Solar Drying $ $14082%14, Non-cost factors include: 1) regulatory requirements, 2) public health and environmental impacts, 3) outlet diversification, 4) operator friendliness, 5) ease of maintenance, plus 6 others.

NC AWWA-WEA 93 rd Annual Conference Recommended Improvements Pre-Screening Platform 14 Free-standing outdoor structure Two mechanical screens for co-settled sludge on top Screening drop to dumpster below JT

NC AWWA-WEA 93 rd Annual Conference Recommended Improvements Pre-Dewatering Facility 15 Pre-Dewatering (2-Story Bldg.) Cake Bins Storage (Outdoors) – Screened solids are pre-dewatered by centrifuges – Discharged to outdoor cake bins using screw conveyors THP FEED PUMPS TO THP CAKE BINS CENTRIFUGES JT

NC AWWA-WEA 93 rd Annual Conference Recommended Improvements Thermal Hydrolysis Process Pulper Flash Tank Reactors (3) Digester Feed Pumps

NC AWWA-WEA 93 rd Annual Conference Recommended Improvements Anaerobic Digesters Prestressed concrete tanks 64-ft diameter Cone bottom Draft tube mixers mounted to concrete cover Digester gas flare Adjacent digester building for pumps, etc. Outdoor heat exchangers for cooling sludge from THP

NC AWWA-WEA 93 rd Annual Conference Recommended Improvements Final Dewatering Building Option A: Reuse Existing Facilities – Refurbish or replace 3 BFPs – Continue to operate centrifuge – Ventilation and other improvements to mitigate corrosion problems – Can continue to use truck loading station Option B: New Final Dewatering Building and Truck loading Station

NC AWWA-WEA 93 rd Annual Conference Recommended Improvements Solar Dryers 19 Eight modules, 42-ft x 435-ft Fans, louvers, controls to optimize temperature and humidity for drying

NC AWWA-WEA 93 rd Annual Conference Recommended Improvements Nutrient Recovery Optional addition for enhanced sustainability Reduce sidestream loading on liquid treatment process Recover phosphorous Third-party responsible for product marketing Can be added at any time Photo Courtesy of Ostara JT

NC AWWA-WEA 93 rd Annual Conference Recommended Improvements Combined Heat and Power (CHP) Engine Generator 21 – Single 1.75 MW generator – Containerized units available – Optional, but recommended for sustainability when THP is implemented – Generate electricity and heat – Requires biogas conditioning system – Engine can be purchased, leased, or procured via 3 rd -party Energy Services Co. (ESCO) Photos Courtesy of GE JT

NC AWWA-WEA 93 rd Annual Conference Recommended Improvements Implementation Schedule 22 PhaseYearDescriptionCost Phase I 2016 Pre-screening, pre-dewatering, thermal hydrolysis, anaerobic digesters, CHP engine, additional cake storage $59.3 M Phase II 2021 Eight solar drying modules, BFP replacement and final dewatering building improvements $26.2 M Phase III 2028 Replace existing conveyance equipment and truck loading station $4.3 M TW

NC AWWA-WEA 93 rd Annual Conference Recommended Improvement Plan vs Master Plan TW

THANK YOU