Anaerobic Digestion of Organics and the Waste Diversion Puzzle. Tej Gidda, PhD, P.Eng

Transcription

1 Anaerobic Digestion of Organics and the Waste Diversion Puzzle Tej Gidda, PhD, P.Eng

2 Overview of Presentation What s AD? An example: City of Toronto Options locally 2

3 What is Anaerobic Digestion? Composting Aerobic (air) No biogas production Contaminants in compost No further processing Large footprint Large process air volume Less expensive Anaerobic Digestion Anaerobic (no air) Biogas produced (~120 m3/tonne) Clean final digestate Digestate processing required Compact footprint No process air, less odour Depends on energy pricing 3

4 Pulping 4

5 Extrusion 5

6 Lights, Heavies, and the Importance of Being Gritty 6

7 Name That Material 7

8 City of Toronto Disco Road Organics Processing Facility Toronto has had SSO since 2002 Single-family residential Plastic bags allowed (any kind) Diapers allowed Pet wastes allowed 130,000 tonnes/year generated Internal processing 8

9 Project Delivery Model Design-Build-Operate 3 years + 1 year + 1 year Request for Pre-Qualification (5 submissions, 2 carried forward) Full systems with emphasis on pre-processing Two submissions to Request-for-Proposals Similar structure for expansion of existing anaerobic digester 4 submissions for RFPQ, 2 carried forward 9

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12 Project Development Capacity (75,000 tonnes/year SSO) Permitting timeline ~ 1 year Design Build timeline Total is ~ 4 years Waste removal and pilling ~ 1 year Construction ~ 2.5 years Project Cost Capital ~ $78 M Operating ~ $88/tonne 12

13 Disco Road Organics Processing Facility 3 processing trains Specific concrete blend for tip floor, with steel cladded walls Equalization/buffer tank On-site dewatering (but not composting) On-site wastewater treatment Dual-fired boilers Fast-acting rubber roll-up doors Aggressive negative pressure ventilation system Inorganic biofilter for odour control with exhaust stack Double-pressing of light fraction to reduce residual waste White roof and rainwater harvesting system 13

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15 Process Flow 15

16 Project Metrics Substantial Performance granted July 1, tonnes digestate/incoming wet tonne SSO 30% solids content 116 m3 biogas/incoming wet tonne SSO 65% methane; 1000+ppm H2S Residual waste about 12-15% of incoming SSO 50% moisture 4% of incoming material is grit 200 m3/day of wastewater generated Stack odour emission of ~1,500 OU/m3, less than 1 OU at receptors 16

17 Issues for Cities like Halifax ICI organics are they really that contaminated? Pre-processing exists to deal with IC&I organics Navigate to bagged systems to further promote diversion? Modular systems that can expand over time and utilize existing composting capacity at the back end Co-location avoids trucking cost and NSE restrictions Much more feasible to reach CCME 2005 guidelines or maturity CFIA fertilizers Compost leachate (net water deficiency versus digesters) Higher value final product 25,000 tonnes/year of organics ~ 1 MW of electrical generation ~ $1.5M per year of revenue under 17.5 cents/kwh COMFIT rate 17

18 Thank-you! Questions? Tej Gidda, PhD, P.Eng