1 / 36

DCWASA Biosolids Management Plan: Thermal Hydrolysis, Advanced Digestion, and Green Energy Production

jersey
Download Presentation

DCWASA Biosolids Management Plan: Thermal Hydrolysis, Advanced Digestion, and Green Energy Production

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. DCWASA Biosolids Management Plan: Thermal Hydrolysis, Advanced Digestion, and Green Energy Production Chris Peot, P.E. Biosolids Manager District of Columbia Water and Sewer Authority

    3. Current DC Water and Sewer Authority Biosolids Reuse Program 1200 wtpd lime stabilized biosolids Agriculture – 39 counties in two states Silviculture – 40,000 acres permitted in 8 Virginia counties Poplar Plantation on Gravel Mine Reclamation Projects – three sites to date, 400 acre site in West Virginia

    16. Two Composting Projects 25 wtpd onsite facility 200 wtpd contracted facility

    17. Biosolids Management Plan Update 1999 Biosolids Management Plan (BMP) has been updated to: Evaluate potential markets for various products Evaluate new proven technologies for volume reduction Reduce cost – goal is minimize adverse impact on rates Assure long-term viability of BMP BMP Update Approach – 2 Steps Screened potential technologies Performed in-depth evaluation of several alternatives

    18. BMP Update Findings Maintain digestion as the foundation of the BMP Size digestion facility for peak loading Digestion should be pre-requisite to heat drying to increase product market options Use digester gas to produce electricity and use waste heat from power generation Continue land applying while developing a market for blended Class A products

    19. Update Continued The WASA Board, in October 2006, accepted Management’s recommendation to reject the Egg-Shaped Digestion Facility (EDF) bid, due to the high bid price, and placed the project on hold WASA Management recommended continuous monitoring of: Construction bidding environment Regulatory initiatives that could impact the viability of land application Maturing of evolving technologies WASA’s related financial position

    20. Screened Processes for DCWASA Biosolids Management Plan Acid Gas Phase Digestion ATAD-TPAD Thermal Hydrolysis Composting Drying Enzyme Hydrolysis Gasification Incineration Lime Stabilization Mesophilic Anaerobic Digestion Pasteurization TPAD Digestion Vitrification/Glass Pack Process

    21. Criteria for screening Cost (50%) All Other (50%) Process (25%) Ease of Operation and Maintenance (15%) Large WWTP Installation History (5%) Process sustainability (GHG and energy use) (5%) Implementation (30%) Constructability (10%) Salvage value of EDF plans/specs (5%) Site requirements (10%) Ease of permitting (5%) End-Product (45%) Quality – potential for odor and pathogen growth (15%) Marketability and diversification (10%) Product sustainability (20%)

    22. Evolving Technologies Preliminary investigations indicate that: New technologies are now available that were not proven/available when EDF facility design started Some of these technologies produce Class A biosolids with less digestion tankage than the EDF project Evolving technologies reviewed: Thermal Hydrolysis Enzymic Hydrolysis Gasification SlurryCarbTM drying and gasification

    23. Evolving Technologies Findings: Thermal Hydrolysis Employs pressure and temperature to hydrolyze the sludge followed by mesophilic anaerobic digestion Enzymic Hydrolysis Involves an enzymic hydrolysis process followed by mesophilic anaerobic digestion EnerTech Technologies – Slurry Carb Uses heat and pressure to produce a pelletized “e-fuel” end product Gasification – several demo projects planned, none operational yet

    24. Thermal Hydrolysis – Highest Ranked Technology Price tag within our approved budget Proven technology (in Europe) Class A product, opportunities for end-use diversification Gas production, renewable energy (10 MW) Potential for alternative feedstocks (grease) for enhanced energy production Heat (energy) recovery

    25. Carbon Footprint Estimates at DCWASA DCWASA is participating in two WERF research project measuring: GHG emissions off liquid processes Fugitive methane emissions WERF projects are designed to refine some of the assumptions we are currently using. Staff is developing a working model to track carbon emissions at Blue Plains. Uses some emission assumptions Dynamic model that can change as new info is gathered

    26. Goals and Expected Uses Develop a working model for use in determining: impact of plant process improvements impact of construction Auditable estimate for Chicago Climate Exchange (CCX) registration (or other certifying body) in order to: establish a baseline document improvements sell greenhouse gas credits

    27. World Resources Institute Model Scope I, direct, required Liquid stream emissions WASA vehicle use Combustion of natural gas Combustion of biogas Combustion of biosolids Scope II, indirect, required Purchased electricity Scope III, indirect, optional Contract vehicle and activities Fertilizer offsets Carbon sequestration Embodied carbon Chemical delivery and production Employee travel

    28. Biosolids and Climate Change Land application of biosolids: sequesters carbon in the soil avoids the use (and energy associated w/production) of industrial fertilizer helps farmers get through drought conditions via secretion of essential (naturally occurring) plant growth regulators (auxins – ongoing research at VA Tech).

    29. Typical Month – February, 2009 37,704 wet tons recycled net benefit 2,033 MT CO2 equivalent avoided emissions. equivalent to taking 4,611,708 car miles off the road in the month of December (assumes 20 mpg, 19.4 lb CO2 emissions/gallon gas – EPA estimate).

    30. Breakdown of Benefits

    31. Summary of 2008 CO2 Balance for Blue Plains Biosolids Management

    32. Carbon Footprint Effect from Planned Capital Improvements Energy use at Blue Plains 85% of carbon footprint Fine Bubble Diffusers – on-line 2012 8 MW energy reduction Digester Project – early 2014 10 MW renewable energy production Enhanced Nitrogen Removal (ENR) – on-line 2014 0.8 MW energy increase

    33. GHG Emissions Estimates

    34. Carbon Footprint Comparison for Planned Improvements

    35. CO2 value with voluntary trading – Chicago Climate Exchange

    36. Value of potential credits from the digester project ~65,000 metric tons CO2 eq avoided with the digester and FBD projects At CCX value of $2/tonne, = $130,000/yr At $7.50/tonne (value 05/08), =$500,000/yr At ECX 11.5 euros/tonne, = $975,000/yr

    37. Conclusions DCWASA is interested in: Producing a Class A product Reducing production by 50+% Producing gas for power production (10+ MW) Developing a more diverse quiver of options Products for use in ag, energy, and for sale to the public Helps hedge against changes in regulations, politics, and public acceptance Developing DCWASA carbon footprint with post-digestion projections Interested in supporting the development of embryonic and emerging technologies through research

More Related