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Home My WebLink AboutAnaerobic Digestion Feasibility Study - July 30, 2020 Presentation (PDF)Anaerobic Digestion Feasibility Study Surfside Wastewater Treatment Facility Public Meeting https://youtu.be/fF4ydI_uXxs July 30, 2020 1 Agenda •Project Team •Review of Project Goals •Review of Anaerobic Digestion •Feasibility Methodology & Analysis •Conceptual Design •Schedule & Moving Forward •Questions & Comments 2 CEC Project Team •David Gray, Sewer Director, Nantucket •Roberto Santamaria, Health Director, Nantucket •Lauren Sinatra, Energy Coordinator, Nantucket •Kent Nichols, Weston& Sampson •Dan Sheahan, Weston & Sampson •Gina Cortese, Weston & Sampson •Representative from numerous Town Departments MassCEC Assistance •State economic development agency •Mission: grow the state’s clean energy economy while helping to meet the MA’s clean energy, climate and economic development goals •2019 Organics-to-Energy grant for Feasibility Study: $60,000 •Public Outreach Support Project Goals •Determine Feasibility of AD Based on: –Feedstock Availability –Treatment Capacity –Energy Production –Waste Production –Financial Analysis –Evaluation of Project Site, Vicinity, and Community Impacts –Environmental and Permitting Consideration •Anaerobic Digester Conceptual Design 5 Anaerobic Digestion Benefits 1.Create sustainable energy source and cost savings for WWTF 2.Reduce volume of waste sent to Composter/ Landfill 3.Stabilize and increase nutrients in WWTF solids 6 Anaerobic Digestion Technology •A collection of natural biologic processes. •Microorganisms break down biodegradable material in the absence of oxygen. •Process used in many industrial and domestic purposes to manage waste and/or to produce fuels. •Digestate is produced by anaerobic digestion. Anaerobic Digestion Technology Sludge and other organic feedstocks Biogas Digestate Hot Water Mixer 8 Anaerobic Digestion Technology Feedstocks (Input) •WWTF Residuals (Sludge/Bio-solids) •Fats, Oils, and Grease •Source Separated Organics •Brewery Waste •Other Wastes –Septage and Landfill Leachate Feedstock Identification •Identified possible feedstocks and volumes •Data from WWTF & Landfill Records Currently Available or Received by Truck at Surfside WWTF Waste Name Est. Ave. Annual Volume gal/yr FOG/ Grease Trap 8,900 Animal Grooming Trucks 165 Residential Tight Tank 336,000 Domestic Septage 1,760,000 Food Truck Waste 3,360 Equipment Cleaning Plant Water 165 Carpet Cleaner Waste 15,000 Industrial Wastes (Cisco)133,000 Landfill Leachate 1,900,000 WWTF Sludge 2,330,000 Currently Received at Landfill Waste Name Est. Ave. Annual Volume tons/yr Municipal Solid Waste (MSW)/ Source Separated Organics (SSO) 575 Yard Waste 14,000 Animal Waste 180 Feasibility Methodology & Analysis 10 Feedstock Identification •Difficult to quantify portion of MSW/SSO available to digester •First attempted to quantify all organic waste generators –Food Asset Network (2017 WPI) –Contact large, individual organic waste generators •Schools, grocery, hospital, farms, etc. •Positive, but inconclusive responses Currently Received at Landfill Waste Name Est. Ave. Annual Volume tons/yr Municipal Solid Waste (MSW)/ Source Separated Organics (SSO)575 Feasibility Methodology & Analysis 11 Feedstock Identification •Made estimation of digestible wastes present in MSW otherwise sent to Composter •Assumptions: –20% current MSW is digestible –25% of digestible MSW could be reasonably diverted to WWTF •Commercial kitchens, grocery, etc. •575 tons/year of MSW/SSO Currently Received at Landfill Waste Name Est. Ave. Annual Volume tons/yr Municipal Solid Waste (MSW)/ Source Separated Organics (SSO)575 Feasibility Methodology & Analysis 12 Feedstock Identification Waste Name Estimated Average Annual Volume (liquid, gal/yr; solid, tons/yr) Organic Content Strength (High, Moderate. Low) Gas Production Potential (High, Moderate. Low) Recommended as Feedstock? (Yes, No) FOG/ Grease Trap 8,900*High High Yes Animal Grooming Trucks 165 Low Low No Residential Tight Tank 336,000 Low Low No Domestic Septage 1,760,000 Low Low No Food Truck Waste 3,360 Low Low No Equipment Cleaning Plant Water 165 Low Low No Carpet Cleaner Waste 15,000 Low Low No Industrial Wastes (Cisco)133,000 High Moderate/ High Yes Landfill Leachate 1,900,000 Low Low/ Moderate No WWTF Sludge 2,334,000 High Moderate/ High Yes MSW/ SSO 575 High Moderate/ High Yes Yard Waste 14,000 Low Low/ Moderate No Animal Waste 180 Low Low/ Moderate No •Characterized organic content of each •Made recommendations Feasibility Methodology & Analysis 13 •After Digester power loads are satisfied •Available for WWTF demand offset •Assumptions: –Approximate Elec. Energy Value @ $0.28/KWhr –Energy content of feedstocks from industry standards Feasibility Methodology & Analysis Source Energy Yield (KWhr/yr)Elec. Energy Value Sewage Sludge 241,000 $69,000/year Other Feedstocks 114,000 $33,000/year Total 355,000 $102,000/year Electrical Energy Production 14 Heat Production Feasibility Methodology & Analysis Source Energy Yield (MBTU/yr) Equivalent Heating Oil Cost Savings Sewage Sludge 1,150 8230 $22,000 Other Feedstocks 540 3870 $10,000 Total 1,690 12,100 gal/yr $32,000/yr •After Digester heating is satisfied •Available for WWTF building heating •Assumptions: –Energy content of feedstocks from industry standards –Approximate Average $2.67/gal oil cost 15 Digestate & Biosolids Feedstock Solids (High Season): •Total Solids = 5,600 lbs/d •Volatile Solids = 4,300lbs/d (78%) Solids Destruction: •Volatile Solids Destroyed = 2,500 lbs/d –58% Volatile Solids destruction –45% Total Solids destruction Sludge Cake Solids Produced: 1,100 t/yr Net Reduction in Sludge to the Composter: 320t/yr –35%* Feasibility Methodology & Analysis * Lower % reduction than TS destruction due to addition of outside feedstocks. 16 Impact to Surfside WWTF Process Digestate Liquid Returned to Influent •Reduced Solids Dewatering time due to reduced solids to dewater after digestion. Feasibility Methodology & Analysis * Plant currently at approximately 50% capacity during high season. Current Plant design capacity did not include digestate return load. High Season*Low Season Volume (gpd)10,000 5000 TSS lb/d 155 75 % increase in influent 4%4% NH3-N lb/d 95 46 % increase in influent 15%15% 17 Conceptual Digestion Design FOG Cisco WWTF Sludge Storage Tank Storage Tank Blend & Storage Package Gas Conditioning and CHP Storage Tank Digester Digester BiogasDigestate Return to WWTF Dewatering SolidsFiltrateSSO Screening/ Maceration 18 Gas Processing/ Co-Gen Systems Figure from Water Environment Federation 19 Conceptual Design •Construction: –2 Buildings –SSO Receiving and Processing Building & Digester Support Building •2,000ft2 •Slab-on-grade •Single story –3 Underground storage tanks –Feedstock Storage •5000-gallon each •Precast concrete •FOG, Brew Waste, SSO –1 Underground storage tank –Feedstock Blend Tank •2000-gallon •Precast concrete •FOG, Brew Waste, SSO –2 Digesters •200,000-gallon each •40ft D x 28ft H –Site Piping Modifications –Site Work (associated pavement, piping, earthwork etc.) 20 Conceptual Design Surfside WWTF Siasconset WWTF DPW & Landfill Conceptual Design Surfside WWTF Process Area Sludge Processing Offices Process AnalysisEquipment Storage Primary Treatment Advanced Treatment Waste Gas Flare Administration Force Mains Below Grade Proposed Digester Area 22 Conceptual Design Digester Digester Support Building FOG Storage Tank SSO Storage Tank Brew Waste Storage Tank Feedstock Blend Tank Feedstock Receiving & Processing Building Digester 23 Future Miacomet Area Pump Station Anaerobic Digestion Technology Burlington, VT Conceptual Design Costs Approximate Cost Description Low High General Conditions $1,433,000 $1,911,000 Site Work $814,000 $1,085,000 Concrete $825,000 $1,100,000 Buildings $2,759,000 $3,678,000 Process Equipment $3,179,000 $4,238,000 Exterior Finishes & Equip.$195,000 $262,000 Controls & Instrumentation $185,000 $246,000 Total Capital Cost $9,390,000 $12,520,000 Engineering & Permitting $2,160,000 $2,880,000 Planning Contingency (30%)$3,465,000 $4,620,000 Total $15M $20M 25 Conceptual Design Costs Approximate Cost Description Low High Total Opinion of Project Cost $15,000,000 $20,000,000 Anticipated Annual O&M Cost $300,000 $400,000 Amortized Capital Cost $870,000 $1,160,000 Equivalent Uniform Annual Cost $1,170,000 $1,560,000 (Approx. Annual Cost of Ownership) 26 Financial Analysis •Conceptual Level Capital Cost -$15M -$20M •Equivalent Uniform Annual Cost: $1.2M -$1.6M •O&M Costs –Labor and Parts –Likely Energy Neutral •excess heat and power will support ancillary structure heating and lights and possibly some WWTP supplement •Savings –Sludge Disposal At Landfill (@$83.53/t) •$25,000 annually* –Excess Heat and Power Use •$84,000 excess energy annually •$32,000 heating oil cost savings annually * Assumes composter currently achieves approx. 30% Sludge VS destruction (approx. 50% of AD digester reduction). 27 Financial Analysis Possible Revenues –Renewable Energy Credits –Alternative Energy Credits –Feedstock Tipping Fees –Biosolids Product 28 Funding Sources •Low Interest Loans SRF •SRF Grants •Green Energy Grants •Organics-to-Energy Grants •Other Grants (TBD) 29 Evaluation Criteria •Evaluation Criteria & Importance –Capital Cost –Cost Savings/Revenue Generation Potential –Impacts to Neighbors (Visual & Odor potential) –Operational Complexity –WWTF Site Impacts –Landfill Life –Composter Impacts –Sensitive Environmental Receptors –Environmental Stewardship 30 Schedule Completed: •Kick-Off Meeting with Project Team: November 21, 2019 •Community Engagement Report: December 15, 2019 •Initial Public Meeting: February 4, 2020 •Internal Update Call: March 3, 2020 •2nd Internal Update Call: July 13, 2020 •Second Public Meeting: July 30, 2020 Remaining: •Draft Feasibility Study: August 30, 2020 •Final Feasibility Study: October 30, 2020 31 Moving Forward •Complete Draft Report & Address Public Comments •Town Review of Draft •MassCEC Review of Draft •Complete Final Report 32 Questions & Comments •Receipt by August 13, 2020 •Project Page of Nantucket Town Website https://www.nantucket-ma.gov/1616/Anaerobic-Digester-Feasibility-Study 33 thank you